Dear Mark: The Low Carb Flu

Conquering carbs offers a whole constellation of rewards, not the least of which is a steady, brisk energy unlike most people have known before (well, maybe since the whirling age of 10 or so…). People tell me constantly that they can finally make it through the day without being down for the count every midafternoon. They enjoy enough vigor and vitality to weather a whole day’s worth of activity. The busyness of life becomes easier to handle: the energy demands of daily work or business travel, the mayhem and constant commotion of kids, a weekend’s worth of chores and errands, etc. A skipped meal doesn’t suddenly change the agenda to including procuring a bagel or other false pick-me-up. Nonetheless, for some folks, there’s a common, temporary but still bothersome bump in the road on the way to that Primal prize. Though it varies, it often means a couple weeks of mental fuzziness, fog and fatigue. Although your body might be off to the races, your brain can lag behind like a little brother in a stuffed snowsuit. It’s a game of “hey, wait up!”  while the body’s mechanisms and metabolism align themselves. They call it “low carb flu,” and rest assured it’s just as temporary.

Dear Mark,

I just want to know if anyone who has been Primal for some time had any trouble with cognition in the first few weeks. I can hardly think straight, especially after eating, and I am also low on energy. Will this pass??? Besides that, my body feels great!”

Thanks to Jessica for her question in response to Matt Garland’s excellent guest post last week. It’s a common subject of emails I receive.

First off, I should mention that some folks experience the low carb flu, and others don’t. Overall, those who have been lower carb for some time seem to have fewer problems with the transition taking their carb intake down a notch. As rational as it sounds, this trend still isn’t a hard and fast rule. I know a number of Primal adherents who fit this profile and then went on to experience the symptoms Jessica describes. Others I know went from sky high sugars to low carb cold turkey and felt great from day one. Go figure. It might be due to the “sliding  range of genetic variations” I’ll be discussing in an upcoming post.

Although the low carb flu isn’t universal, that doesn’t mean it’s abnormal. For many people, it takes about two to three weeks to move beyond the temporary fog and fatigue. Studies following the physical performance of low carbers showed that initial disadvantages were erased after this window of time. If your body is used to employing easy glucose carbs and now must create glucose from fats and protein (a slightly more complex but entirely natural mode of operation), it can take some time to get up to speed. Rest assured that our bodies can and are doing the job. It simply takes time to work efficiently. The transition actually shifts metabolic related gene expression, increasing fat oxidation pathways and decreasing fat storage pathways. (That’s nothing to shake a stick at!) Within a few weeks, the body should be fairly efficient at converting protein and fat for the liver’s glycogen stores, which provide all the glucose we need for the brain, red blood cells, muscles, etc. under regular circumstances.

The small amount of specifically targeted research on low carb diets and cognition are small and shoddy at best. A recent study, for example, showed minor memory delay during the first week of strict carbohydrate elimination (as opposed to reduction), but further measures were not taken until carbs were reintroduced. By the same token, those on a traditional American Dietetic Association diet exhibited more confusion during the study tests. I don’t think this study offers any legitimate, useful assessment on either diet.

Nonetheless, there’s the sense that we’re stressing the brain and causing damage by not bathing it in a steady supply of glucose. In fact, we may be doing our brains the ultimate favor. Recent research has pegged Alzheimer’s as a kind of “type 3” diabetes, a disease related to insulin resistance. Truth be told, our brains can function on ketones, fat-metabolism byproducts and key energy sources in low to very low carb diets, which some say may be even healthier yet for our noggins. Check out Jimmy Moore’s interview with Dr. Larry McCleary, a respected neurosurgeon and author of The Brain Trust Program: A Scientifically Based Three-Part Plan to Improve Memory, Elevate Mood, Enhance Attention, Alleviate Migraine and Menopausal Symptoms, and Boost Mental Energy.

Keep in mind also that people in low carb transition can genuinely shortchange their physical needs when they aren’t eating enough fat or when they’re pursuing high intensity exercise routines lasting over an hour, which send the body’s glycogen stores into a nosedive to the ground. I hear this from CrossFitters and P90Xers who insist on maintaining their daily high intensity while transitioning to Primal eating. This isn’t to say that you can’t exercise more intensely for longer on a Primal Blueprint diet (although there’s no real need to for perfectly solid fitness), but more than an hour’s time for most folks requires some extra carbs when glycogen is depleted. If you’re bothered by the mental fog even without intensive exercise, ease up on your carb restriction by adding 25 grams or so to see if it makes a difference. Listen to your body and gauge your sensitivity. Rome wasn’t built in a day, and you’re not going to compromise your overall benefit by taking it slowly.

As any Primal buff would attest, this temporary setback pales in comparison to the benefits once the transition has passed. Without the persistent carb-induced peaks and crashes, you should enjoy a measurable boost in energy – steady and stable – in no time. Hang tight, and know you’ll be on the other side of the hill soon! In the meantime, take good care of yourself with a little extra shuteye and maybe some well-timed green tea for a modest boost when you really need it.

Avid Grokkers: what words of experience do you have for Jessica and other new folks at the Primal table? Be sure to share your thoughts, stories and words of wisdom. Thanks for reading and keep your questions coming!

About the Author

Mark Sisson is the founder of Mark’s Daily Apple, godfather to the Primal food and lifestyle movement, and the New York Times bestselling author of The Keto Reset Diet. His latest book is Keto for Life, where he discusses how he combines the keto diet with a Primal lifestyle for optimal health and longevity. Mark is the author of numerous other books as well, including The Primal Blueprint, which was credited with turbocharging the growth of the primal/paleo movement back in 2009. After spending three decades researching and educating folks on why food is the key component to achieving and maintaining optimal wellness, Mark launched Primal Kitchen, a real-food company that creates Primal/paleo, keto, and Whole30-friendly kitchen staples.

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200 thoughts on “Dear Mark: The Low Carb Flu”

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  1. You have to believe. It’s as simple as that.

    Write down EVERYTHING you eat and go by the numbers. The Daily Plate on is an EXCELLENT resource to track your eating habits. Pick a healthy protein/fat/carb ratio (1/3’s is not a bad place to start) and stick to it. It WILL get better. And once you’re better, there’s no way you’ll ever want to go back to the “old way.” You’re going through “carb-junkie detox,” and you just need to grind your way through it.

    If you’re an athlete, you’ll obviously need some extra carbs either during or post workout.

    After 90 minutes, your muscles will be out of glycogen, so if you’re going over 90, you’ll need to start taking in some sugar prior to that. Everyone’s different, so let your body be your guide and don’t go crazy. You don’t need to pound down a half-dozen cliff shots prior to a ride like I see people doing all the time. There’s a lot of healthy and creative solutions. I stick a honey bear in the bento bag on my bike for longer rides. Just based on experience, I know what timing of sugar intake is enough that I recover easily and don’t feel like dookey post-workout. Cheap, simple, natural, and best of all – it works great.

    If you were eating hard-core paleo and did a long, hard workout with no carb intake, that could be the reason for your suffering. It took me a solid week to recover from one of those mistakes. But you will recover if you let yourself and life will get better.

    1. “Pick a healthy protein/fat/carb ratio (1/3’s is not a bad place to start) and stick to it.”

      Umm…what? I think you want the Atkins forum over there—-> 🙂

      1. Hey, I’m not shilling for anyone. I went to nurse/dietitian that specialized in setting up nutrition plans for triathletes. I didn’t list *my* ratio because my ratio was custom tailored for me based on actual metabolic measurements. I wouldn’t know an Atkins plan from a hole in the ground.

        My only point is that if people ate in 1/3’s, that would be at least *half* the normal number of carbs and double the protein the typical person is eating in a day. I know Mark advocates less carbs than that, but for many people, looking at a pie chart on Daily Plate and just making it into three equal “slices” if you will, would be a dramatic step in the right direction.

        Start there, then let body awareness guide you the rest of the way.

        1. I didn’t think you were shilling, I was just surprised that you were posting on a site about primal nutrition, among other things, two things that go so entirely against the essential nature of primal eating: weighing measuring and recording and eating such a huge percentage of carbs.

        2. I think if you are trying to lose weight you may have to count calories (I know I need to because even eating primally I can accidentally eat too much because I’m eating calorie dense foods). But 1/3 carbs is definitely too high for me (I eat an almost ketogenic diet).

        3. Thirds isn’t primal – my breakdown is 20% protein, 15% carb, at least 60% fat (by calories) balance is a glass of wine – that gives me just under 100 g carb tops per day and I’m an athlete.

          I had massive detox for 36 hours – shakes, mental confusion, night sweats, the lot – real cold turkey stuff – that was cutting all grains and added sugar from my diet – I was high carb low fat CW athlete nutrition. After that I felt like a new person.

          Believing and having faith is the key and as my brother said tonight when he phoned (75 lbs lighter this year)Primal Law 0 have a Grok buddy to support you, failing that keep reading MDA!


        4. Did you have to mention pie? I just started the switch to Primal eating two days ago. I don’t feel like I have carb flu, but I wasn’t a huge grain eater really. My weakness is desserts and treats. Luckily for me though my cravings are most intense just before menstruation begins and I chose to begin eating primal just after my cycle ended (over share?). Hopefully by the time the intense cravings come around, I won’t have them this time. Only time will tell but so far it’s been easy, I’m sure I’ll get hit in the face by those cravings in the future, but I’m trying to think positive and hope I can breeze through those hurdles and continue on down the path. I’m quite pleased I’ve made it the past two days, particularly with the chocolate chipp cookies sitting in my cupboard as we speak. Wish me luck and LOTS of will power!

    2. Not sure how to respond to John C directly but a lot of people use the Biggly software specifically for tracking their progress with primal eating and workouts. Measuring and using progress as motivation is hardly breaking rules or something..?

  2. “but more than an hour’s time for most folks requires some extra carbs when glycogen is depleted”. Of course everyone is different but my experience over the last 6 months of gradually building my capacity is that I can routinely do a 2500-3000 yard masters swim set on a saturday morning and then go ride 30-50 miles with time trial effort, hill sprints or hill repeats depending on the workout, all on water and salt tabs – and Trust me – I am no genetic marvel – very much a 47 year old middle of the pack age grouper. It just take a little time.

    1. I just did a 34 mile bike ride without carbs. eggs for breakfast, then just coconut water with coconut oil added for some fat.
      Then there were the others. Some younger riders were participating, I guess for the first time, and the parents were encouraging bananas and cookies “because you need lots of carbs for energy when riding”.
      I wonder if that’s why some many riders I see have pot bellies?

      1. Check the carbs on coconut water. You took in at least as many as those eating bananas.

        How can some people here be so blind to the nutritional makeup of their food in order to maintain claims of “being low carb”?

        1. And you seem a little confused about being low carb vs primal vs a lower carb athlete

      2. You’re an RN, Dave? And you seriously believe people get potbellies from eating too many bananas?

        Produce even one such person and you’ll likely make medical history.

        Get real.

        1. I didn’t say coconut water had no carbs. My point was that loading up on excessive carbs over a period of time can result in mesentery fat accumulation. I know this from experience. I had a 30 lb gut on me from my high carb diet. I was real good at hiding it too. I had backaches from sucking my gut in all the time.
          As for the coconut water, I used that instead of the typical “sports drinks” because It contains similar levels of electrolytes as those found in human blood, and in fact was used in place of plasma in the Pacific theater in WWll when supplies of plasma were low. That and it’s not an artificial. Yes it has carbs, 14 in the container I drank. One banana has 23 grams, and I’d eat 2-3 on a 30 mile ride in the past, along with cookies and oranges. I also didn’t say how much I had. So let me be more specific; 11.2 oz (14 grams), with 5oz of oil, (0 grams). The rest was water.
          So, 14G carbs vs. a typical ride for me with 75-100. That was my point.
          And then I went and did two hours of martial arts. Then I came home and had dinner. My point there being it wasn’t necessary for me to go home and load up on carbs and “recover”.

        2. Interesting debate!

          I just rode a Sportive – 81 miles, and I rode hard, 6,000 ft climbing and clocked 4:24 (average heart rate 80-85% of max) – around 10 g of carb from raw fruit/nut bars an hour with water and electrolyte salts … the longer you train low carb the more efficient your body becomes. And breakfast was eggs and bacon with some full fat Greek yog and berries with a teaspoon of clear honey 🙂 … carb loading – who needs it!

          Watch this space for Primal endurance activity in action, I start on 12 June …

          May be I am a genetic marvel – but I doubt it – I’m certainly super efficient at fat burning for fuel though.

        3. It is a fact..bananas do cause pot bellies. Have you ever seen an ape withut a pot belly?

        4. Massive supply of fructose, are you kidding? Goes straight to the liver and turns into fat. Be one of these people who eats pounds and pounds of fruit daily (only they make it into smoothies) without also getting enough choline to counteract it and you’ll wind up with a lovely case of non-alcoholic fatty liver disease.

          It doesn’t always mean a pot belly but if you could get the pot belly without the NAFLD, believe me, you’d rather have the pot belly.

  3. Interesting. If I recall, I went primal on a Monday or a Tuesday and I began having flu-like symptoms before that first weekend.

    After 4-5 months of success, my wife tried to go primal and she too had flu-like symptoms her first weekend. Glad that it passes relatively quickly.

    1. Any idea how long the flu-like symptoms can last? My husband didn’t get them, but now I have been going primal for a month and still have flu-like symptoms. I keep hoping this gets better because I really want to go primal, but honestly it’s making it hard. The last 2 weeks have been a nightmare… My guess is that my diet was so high in carbs and sugars my body is just freaking out, but i feel like i can’t take much more.

      1. The flu-like symptoms are the die off of the bad bacteria (including candida) in your intestines. They aren’t getting all the sugar and gluten to eat, so they are dying and releasing all their toxins all at once. I guess if you had a lot, it could affect you for a while. My niece has over 17 food allergies including gluten, dairy, and corn. She went through the mill with the die-off symptoms.

      2. I’m on week three and I feel about as good as a dropping from a grass-fed cow. My body might be healthier, but I still feel like s***. If I don’t get any relief soon I might resort to adding more carbs in the form of sweet potatoes and maybe some whole-fat dairy w/ fruit. (I’ve been eating sweet potatoes and fruit, just trying not to go overboard on them.) I don’t want to give in, but I’ve honestly felt like I’m not safe to be driving at times. This blows. I want to feel all the wonderful things that others have reported!

        1. If you intake enough oils in your daily routine, you won’t feel like that at all. Try to make a 3 egg omelette in the morning with olive oil. Then have a large salad with olive oil and balsamic vinegar in the afternoon. For me personally, I think it is the fat that makes me feel satisfied.

        2. me too! that’s why i started asking around about low-carb fatigue. i’m like a zombie, and have been for over 3 weeks now… and i’m also dangerously close to stoking the carb-o-retta…

          did you notice any progress/positive change yet?

        3. Good news folks–I’m feeling much better now! Hopefully this means you will too! I think it just takes some people more time than others. You can experiment with your fat/protein/carb ratios all you want, but in the beginning, I think you just have to do whatever works (if that means a few more potatoes or fruits or rice, so be it). Now that I’m on week 8, I don’t feel the need to eat too many carbs. I’ve also added in some dairy in the form of goat yogurt and grass-fed cheddar. I love being able to go for long stretches without eating and not feel like I’m about to pass out with hunger (previously I was consuming about six small meals a day and if I skipped one I’d get cranky real fast). I’m still adjusting and seeing what works best for my body, but overall I feel better and trimmer (even though the numbers on the scale haven’t dropped drastically, my clothes feel looser and I think I look better, so isn’t that all that matters? 😉 ). Before the Primal Blueprint entered my life, I was a carb queen and could inhale a bowl of pasta no problem. Now I look at it and think of how crappy I would feel afterwards. Keep trying you guys! Once you start feeling better, then you can access to see if this all has been worth it.

        4. I don’t know about intaking “oils” but fat generally, yes. Eat some animal fat if you’re not already. Olive oil’s nice but not as the only fat you intake.

      3. Yes, when does it end. It is 3 weeks tomorrow for me (cut out all processed foods but I had only been eating after lunch chocolate 500 calories) and fruit. I still feel as if I have a germ, sore eyes, tired all the time (yet in bed mostly asleep for 8 – 9 hours a night), nose slightly blocked as if I have a mild germ about to come out.

        You would have thought by nearly going into week 4 it would be over by now. Also only lost a pound in weight at best. I am however sticking with my 3 meals a day with a brown carb, eg baked potato, brown basmati rice or sweet potato with skin. I suspect giving up those “brown carbs” is not going to make me any happier, just worse so do not want to be rid of them or I could derail the whole process. My cravings for sugar have gone but the feeling that someone is sitting there draining energy from me all day is absolutely horrible and I wish I knew if I had some other kind of germ or if it is due to giving up fruit. I do not want to reintroduce fruit or dried fruit as I have always been addicted to it and it is a kind of triumph I have managed 3 weeks without any.

        1. No, you probably better drop the brown carbs. Kind of missing the point there.

          I can tell when I’m eating too much starch because I wake up groggy. If you are just hanging “in between” SAD and Primal you are going to cause more problems than you solve. Besides, that stuff’s almost empty calories. Take up the calories with something more nutritious.

        2. I disagree w Dana about “causing more problems than you solve” as well as her statement that potatoes (both white and sweet) being empty calories. All potatoes, white, red, sweet and yams, all high carbohydrates and (a blasphemous) starch, nevertheless have a lot of nutrition.

          However, I do agree w Dana on the fact, to become fat-adapted and in a ketogenic state, a person needs to follow a VERY low-carbohydrate diet. Otherwise one will never fully fat-adapt. Unfortunatley, for some people, the process of adaptation, can be a brutal hell to attain. I’ve heard it said that it can take as long as 6 weeks. (I was practically immobilized w fatigue for close to 3 weeks when I decided to cave-in and eat a spud) The problem, at least for me was: who has the kind of time to hang out feeling miserable, unable to function until our body heals and decides to adapt? Most of us have all sorts of commitments, families, work etc.

          Hence, my potato defense…

          According to Cate Shanahan MD, a major player in the low-carb/ketogenic community of doctors states: that adding healthy carbs, like sweet potatoes and even (demonized) white potatoes to our current low-carb diet in extreme moderation and on a temporary basis (key words: moderation and temporary) is a healthier approach than going “cold turkey”. After all, initially we should be starting at “low” carb not “no” carb. Shanahan says: for those who struggle w adaptation, fatigue is your body’s way of fighting back. Adding small amounts (according to each individual) of slow-burning carbohydrate to our diet can be part of the process that eventually will take us, if we choose to do so, to a VLC ketogenic diet and lifestyle. A gradual type of titration if you will…

          Dr.Shanahan maintains that it doesn’t make sense to go from a highly processed high-carb standard Am. diet (SAD) to an extremely low-carb Ketogenic diet and expect our bodies to feel good about it. Those that do adapt immediately or within a few short days are the exception.

          We don’t lose weight to get healthy. We actually get healthy first, then we will lose weight. We do this through the 4 pillars.
          (1)Diet (2)Sleep (3)Stress reduction and (4) Appropriate exercise.

          It has been my experience that working my way toward a specific dietary health goal, by using dietary tweaks along the way, is more beneficial and rewarding than jumping in w both feet and feeling miserable. As many have already expressed, adaptation is a strange phenomena… some folks adapt within a day or two and (at least appear to) live happily ever after. The rest of us are blasted by fatigue, brain fog, muscle cramping, adrenal/thyroid issues as well as hair loss instead of weight loss.

          Lastly, I think more research is in order.

  4. Agreed with Eric. I experience the same thing. I was wondering why I was still hungry and tired all the time when everyone spoke of energy spikes and feeling more fulfilled after meals.

    I gave it 2 weeks pretty strict, and soon, I was off to the races! The main thing I have noticed is my recovery time after a touch workout (I’m an avid CrossFitter) has decreased dramatically, and I’m not NEARLY as sore the next day.

    Another thing I’ve noticed is a different kind of body awareness. I’m now so much more aware of when I’ve had too much sugar, even in the form of fruit, or too much meat. Now, when I eat even a little bit of bread I feel hung over the next day.

    It’s incredible the changes you’ll feel, and most certainly see. I, personally, did not have any weight to lose when I started eating more Paleo, but I have gotten smaller (I lost a pant size) and gotten much leaner in only 2-2.5 mo’s. I do “cheat” sometimes, but those moments only serve as a reminder of why I eat this way. The next day or even within a few hours I can feel the grossness coming on.

    My main point? Keep with it! Write down EVERYTHING you ingest (including drinks, gum, snacks, even if it’s just one peanut…they add up). After a week, take a look back and see how you did and how the balance is. Remember that a balanced Paleo diet is key, not just eating foods that are Paleo. Too much fruit can give you a sugar high, and too much meat can make you feel sluggish (it does for me, anyway). Learn to listen to your body, and your brain will catch up.

    Best of luck!

  5. To me one of the big benefits of eating Paleo aside from health is *not* writing stuff down, *not* weighing and measuring.

    If I wanted all that stress and hassle in my life I’d go on a diet or something. 😉

    1. I agree, but when I feel myself falling off the bandwagon, I start writing everything down to help myself get back on track. That’s also how I started and it helped me stay away from all the nasty stuff out there. Writing things down helps me check the balance in my diet, too.

  6. Great post! I too experienced some issues when I went Paleo. I was mostly just sluggish, more tired than normal during the day. Felt like taking a nap, which I never used to feel. It got better though, mostly after about a week or two. As the post suggests, just stick with it and those ‘carb withdrawls’ will eventually pass.

  7. I remember getting “carb flu” after doing GOMAD (gallon of whole milk a day) about a year ago for around a month ( went w/ my strength training at the time) – After which I switched to only having starchy carbs post work out only. I didn’t know what was wrong with me, I was totally shattered for the first week. Over time my body adapted better & better as my diet became more primal over the next 6months or so.

    1. Why would you want to breast-feed if you were doing strength training?

      1. That, sir, is a stupid response and no better than troll-bait.

  8. No carb flu experience here 🙂

    I think newbies need to just take baby steps. There is no need to rush things. You have probably been eating the way you were eating for several years… so why try to all of a sudden cut your carb intake in half or more overnight? Ease into it… cut 50 carbs for the first week then 50 more… or even do it in 20s.

    I just try to advice baby steps in everything in life… we are all so rushy rush! Life is NOT short. We shall all be grateful that we are all living!

    Good luck all newbies – you will get to the magical feeling soon when you will NEVER look back to your ole ways! Living primal is like living in an entire new world 🙂 🙂

    1. Some of us like to just rip the Band-Aid off and get going. It may be too much for some and cause them to give up but for others it’s best to get it out of the way while the motivation is still high.

      I know when I first tried Atkins years ago I only made it 3 days the first time and gave up. The next try, I cut out sweet tea and fries for a month first then tried induction and I made it through. Too bad I didn’t find Paleo back then cause all the fake bars, shakes, maltitol/sorbitol chocolate bars, and absolute “low-carb” crap combined with too much protein and too little fat (and the wrong types) caused me fail. I started Atkins style 5 months ago and found Paleo 1 month in and have been going strong ever since.

      1. You don’t have to use the shakes and carbs to do Atkins. I’m kind of peeved that I keep having to tell people this. I know this is an old comment I’m responding to, but I feel compelled to correct misconceptions.

        The bars and shakes were created to supposedly make the diet easier for some people (and, yes, to make money for the company). But you can do Atkins without once touching them. You can also do Atkins with just Primal or Paleo foods. While Atkins does have a list of foods you are allowed to eat in various phases, it does not mean you are *required* to eat all those foods. For example, up to the last book Dr. Atkins published while he was still alive, soybean oil was allowed. But I could avoid soybean oil and still be Atkins-legal.

        Atkins is useful as a tool to break addictions and find one’s personal carb tolerance. In that light, for some people, it is invaluable. Let’s stop pretending otherwise; I’d be willing to bet everyone slamming it never bothered reading the book anyway. FWIW, one of Dr. Atkins’s motivations for encouraging people to try low-carb was that it was more like the way “cavemen” used to eat! Sad that he was probably more tolerant of the idea of Paleo than Paleo people are toward his diet today.

    2. Do you ever have problems sleeping on low carbs? I feel much better since I switched to eating fat/protein foods for breakfast and lunch, but if I eat a meal of meat and veggies alone for dinner I just won’t fall asleep, so I usually toss in a few pieces of fruit for desert to help induce the sleep. I did a little research and found ketosis tends to increase the time in deep sleep in exchange for REM sleep. I was just curious if you had any experiences with this, or what your thoughts were?

  9. I’m one of those that went from high carb (whole grain breads and soy spreads) to the PB cold turkey and felt great since day 1.

    BUT, after 3 weeks exactly I had a HUGE sugar craving…what I didn’t know at the time was what Mark states in his article: Don’t go low carb + work out more than necessary, which I did every day for 3 weeks straight.

    I gave into the sugar craving because I did not know how to fight it…i binged on mexican pastries for 2 days straight.
    Not smart but it worked at the time. I have been 100% primal ever since for little over 2 months now without a single craving.
    Those 2 binge days made me feel so crappy that it’s not worth repeating if it ever happens again.

    Now I have pure grass-fed/finished kidney fat to fill that hole. Works like a charm:)

  10. You’ve got to make sure you eat enough fat.

    A lot of us have been brainwashed into being afraid of eating fat. I got over my low-carb flu after cooking up all the bacon in the house and eating as much of it as I could. Felt awesome immediately after that.

    Now, whenever I feel run-down I have some pastured eggs or raw milk and it picks me right up.

  11. I struggled with cravings but not with any mental stuff. My skin got oily and I broke out as my body transitioned to a high fat diet, but thankfully that only lasted about three weeks to a month as my body cleansed itself. I read a while back that some new comers were struggling with the same thing.

  12. Thanks for this post Mark. I definitely got the “flu” after going Primal. I have had a few bouts of anxiety in the past and these symptoms seemed to exacerbate the problem. As a cyclist and runner, my body was used to a high-carb diet and rebelled when I cut them out. I actually felt so bad that I reintroduced some brown rice, some potatoes and sweet potatoes. Now I realize that I was doing too much too soon. For me anyway. I’m 6’3″ and 199 lbs. so I need to make sure I am getting enough calories and especially fat while reducing carbs. Time to begin again. This time a more gradual approach is in order I think.

  13. I’ve been 90% primal for about 3 months. My 13 yr. old daughter just started last week. Neither one of us has had any negative withdrawl-type symtoms, though we both had different eating habits before going primal.

    I can’t say for sure why this is, but we both eat a primal diet of about 60-65% fat, and shoot for .8 grams of protien per lb. of lean body mass, and a carb intake of 50-65 grams (per day). We don’t focus on calories, but they usually work out to be around 500 per day less than needed to maintain weight.

    We use FitDay to keep track of everything we eat for the first couple of weeks. It helps in the transition phase to see how the actual numbers add up. I didn’t find it necessary to keep track after that.

    My daughter wanted to go primal after seeing what I had accomplished in 3 short months. I was about 45-50lbs. overweight. I’m down 20lbs and feel terrific compared to before. We both are looking to be close to our fitness goal by the end of September. At that point we should both have reached “before & after” status!!

    For those of you just starting, get excited. This works. This is right. This is the real deal. Just follow the Blueprint on this blog. All of it.

    A word about exercise. Don’t worry about motivation at first. You will definitely want to exercise more and more after you begin eating right and the pounds start coming off and energy levels rise. You won’t need anyone to tell you to do it, or make you do it. You’ll want to do it.

  14. I never got the “low carb flu”, but it sounds like what Masters Ultra Runner Rob Evans had happen to him. He is interviewed by Scott Dunlap over at his very popular “A Trail Runner’s Blog”
    and talks about 3 tough weeks after going high fat,high protein,low carb, but how this diet has been a big part of his newfound success.
    Lots of ultra runners and endurance athletes going primal these days, with great results.

  15. I started exactly one week ago–the first few days were ROUGH. I had zero energy, making my CrossFit workouts nearly impossible. I read a bit about easing into it, and had a sandwich here, some pasta there…I was maxing out at 1,000 – 1,100 calories per day…not good. Now things are better, but I don’t feel any better than I did before I started Primal eating. If nothing else though, following this site has eliminated chips and beer (almost) from my diet. Keep up the excellent work Mark.

  16. Mine lasted for 6 foggy weeks. Everytime I would get close to breaking through, I would give in to the sugar craving and was too scared to eat THAT MUCH FAT lol. Hindsight, as usual, is 20/20 and I should have just brought on the bacon/avacado/coconut oil/steak until I felt better.

    In other news, if you fall off for a while then return to HF-LC, the “flu” lasts considerably less time… I’m guessing because you’ve already adapted once before, so it’s not a “new” thing to your body.

  17. Sometimes the low-carb flu is a result of a lack of veggies. In my previous low carb experiments I ate only meat and cheese, very acidic of course. That is what got me sick until I brought up the veggies again.

    Someone mentioned above that they experience hang-over symptoms from white bread and processed flour products. I get that too now!

    1. All protein, even plant protein, creates acid in your body, but your kidneys are adapted to buffer that acid. If you eat animal protein, it even comes with its own buffer: the amino acid glutamine. You are not ever going to make yourself “acidic” enough to get sick unless something is wrong with your kidneys. You might have been reacting to the casein in the cheese, though. Lots of times when people want to transition to Paleo or Primal due to gluten sensitivities, they have wound up with casein sensitivities as well. And there is a lot of casein in cheese.

      Veggies have some utility for both micronutrients and hormetic effects (look it up), but a human being can go entirely meat-only and do just fine. In fact we would have had to do so during glacial periods if we lived far enough north, and of course the Inuit did that for large portions of the year before whites encroached on their territory.

      1. I like you. Everywhere I go the veggies follow me…::sigh:: first you defend dr atkins, who saved my life ten years ago when was first dxed as a type 1.5 diabetic, then you defend my food choices hehe. Definitely like you. Hi, Im Marie 🙂

  18. I seem to think the low-carb flu is related to carb addiction. Wheat and other grains contain opiates and when people break this addiction, as with any junkie they go cold turkey for a while.

    1. I totally agree with this. I think the severity of mine is because I was unaware of how much my mood was relegated by sugar before. It was sneaky because it was mostly fruit and chocolate and alcohol, not grains. But all the advice is extremely helpful. More fat is a hrad thing to wrap your head around if you previously listened to CW…but it definitely makes a difference for me. But it’s something I have to remember and then force myself to eat! Good luck everyone.

  19. Never got the carb flu. I did get depressed once just thinking about no carbs….lol. I love the no or little carb lifestyle. To make it easier on your self, plan some cheat days here and there, this will give you something to look forward to on your journey. Remember to set your goals, long and short term and take it one day at a time. My mother gets brain fog just at the thought of no carbs….lol

  20. I had about 3 days of low-carb flu, I haven’t measured *anything* (calories or ratios) and I’ve been losing weight really quickly.

  21. I’ve been doing Paleo for athletes for about 1 week. I was really tired after about 5 days but today I’m feeling good. My problem is that I’m still getting cravings, but I just eat berries to try and subsided them.

    1. Those cravings go completely away at 20 grams of carbs a day or less. You might try different levels of carbs and see what works for you.

      1. I went low carb (not paleo) 8 years ago and settled into about 60-80 carbs a day. The carb cravings completely left.

        I went back to a more CW diet (grains are everywhere, it became hard to fight). I stopped losing weight and this little pot belly just won’t leave.

        I’ve started stumbling towards a paleo diet this time; the whole approach just seems so sane, and I could use a little more sanity in my life. I’m back to having those cravings but know they’ll leave when I hit <100 gms carbs for a week.

        p.s. I don't think I ate enough fat last time…got to find some good bacon (everything in this town is full of "…ites" and "…ates")

  22. into week 3 as of yesterday, and just now coming out of the fog and grog of carb flu. My diet was heavy grains and legumes just prior to Primal, so I imagine that I am in for a bit of a longer battle shaking it all. Feel good though, and some days are better than others. My workouts definitely suffered, but I am finding my new sweet spot in regards to my Kettlebells and lifting. I am having a tougher mental battle over the bacon thing right now…
    all in time I suppose!

  23. The closest I’ve come to the low-carb flu was a few splitting headaches when I tried reducing my carb intake to near zero. Eating ad libitum paleo was keeping me a bit paunchier than I’d like, and it took calorie counting on for a couple months to lose the extra 13 pounds. During that time, my daily carb intake ranged from about 80-120 grams, which was enough to prevent ketosis and headaches, but not so much that it created that voracious gnawing hunger that larger amounts of carbs do. On days when I was less physically active I could eat as few as 1500 calories and feel only the gentlest of hunger impulses.

  24. I’ve been “easing into” primal over a few weeks now and have not experienced anything flulike; However I had a carb overload this weekend and felt like utter crap. Go figure.

  25. It hit me at the start of my second week and lingered for a week, but only two days were like being out sick with the flu. The rest was just a little weak and foggy.

    What made this easy for me though was I started with high blood pressure and high blood sugar and both numbers were falling into nice normal ranges during that second week.

    It also helped to have a wealth of information available describing what I was experiencing. So thanks for adding to that, Mark. If I ever win the converts I’m working, I’ll point to this post BEFORE they get hit.

  26. i realize we are in a sense, detoxing from conventional wisdom but more literally, from carb overload.

    is there a connection/similarity between going primal and detoxing?

    while i haven’t gone through these flu like symptoms while going primal, i have experienced it going through fasts and cleanses.

  27. I feel your pain girl!!!!! My goal was to do no carbs, no sugar, no fruit and no caffeine for a month. I lasted about 3 weeks until I had some birthday cake. Now I’m back to feeling that icky feeling, however, it’s not as bad as it was the first time. I binged for about a week on that dredded cake. However, I know now that your energy does pick up and what kept you going before (carbs, sugar, caffeine) is no longer needed. Water replaces the caffeine and I ALWAYS will have some protein and veggies with me at all times; because good decisions never happen if you’re not ready with your food. Unless you’re that diciplined. 🙂 I could feel my motabolism pick up when I’d get hot every so often. It definitely will be worth it once you get there. I’m on my way again. This time with more self control! 🙂

  28. I definitely felt the pangs of the Primal flu…my body was achy, my head hurt and I was exhausted but could never fall asleep.

    It lasted about 1.5 weeks and then BAM I felt awesome! I now spring out of bed and feel full of energy all day.

    I’m slowly converting my friends to Primal, but I always warn them of the flu they’ll feel at first. It’s worth it to stick it out though!

    1. I am having this issue right now but it’s so bad, I wake up with huge headaches in the morning, I am super exhausted but can’t fall asleep, really light headed if i stand up too quick, I feel lethargic and down. I ate some white bread today because i thought it would help. It didn’t. I don’t have any cravings though which is a bonus I guess.

      1. @L – Your symptoms sound similar to mine – total exhaustion, unable to sleep, feeling weak, dizziness when standing…I’m now on day 13, and it is the first day since starting that I feel half-way decent. It hasn’t been all bad though; my skin is clearer and I’ve lost 7 lbs.

      2. I have these kind of issues, an last time, end of the day and feeling really dizzy, I cheated with a big smoked meat sandwich. Feeled totally okay after. I tought that time that it was the bread from the sandwich that get me better just after the meal, but not i’m beginning to think that maybe it was the big amound of protein+fat

      3. im soooo with you. It is really getting me down. i am absolutely smashed

        1. You guys totally just need some more potassium, sodium and magnesium. Make yourself a yummy drink with some crystal lite and add some diet salt (potassium chloride) and some Dead Sea salt (sodium and magnesium) and take a magnesium supplement. You’ll feel a world of difference.

  29. I have also been easing my way into Primal (just bought the book too!) and with the exception of Memorial day weekend and this weekend (big party wedding) I’ve done pretty good, and have notice very little side effects during my transition.

    I do have one question though, since its my goal right now to be selected for my state police soon, how should I go about my workouts? Running is a big deal in the academy (normally 30-45 mins of running a day), and I probably shouldn’t be avoiding it as prescribed by the Primal diet. I did purchase (and began working out with) a kettlebell, and have been doing sprints, but can’t envision getting away with out running for extended periods of time. Can anyone help or provide some tips for me?

  30. Funny, I had suffered from this type of foggy-thinking syndrome for a couple years. Once I dropped the gluten grains from my diet my head cleared up.

  31. Hi, everyone. This is Jessica, who inquired about the cognitive issues when switching to Primal eating. Believe it or not, my Primal journey began over a year ago when I first began eating Paleo-but there was still a considerable amount of fruit in my diet and it kept my on the carb hunger roller coaster (I think). Then I found Mark’s site and things got better. I was 100% Primal for about 6-7 months. The thing is, I had some weird metabolic thing going on (doctors found nothing) and was hungry all the time. I don’t know if it was recovery from years of high carb (“good” whole grains!) eating, severe chronic cardio recovery, calorie restricted diets for many years, or just randomness…probably some combination, but the caloric restriction probably wrecked my metabolism. Fortunately, it’s now back to normal. Despite keeping the carbs low (only from veggies and some fruit) during my first Primal attempt, I couldn’t get things to click. I don’t know if I was super sensitive to carbs and high sugar veggies like carrots??… So, I remained in the brain fog. I completely abandoned the Primal lifestyle, despite loving it, for various reasons completely unrelated to Primal (that’s another story!), but kept feeling the pull to come back. I’m happy to say that after my hiatus I’ve been Primal again for 3 weeks, but this time, no sugar-not even fruit or high-sugar veggies. Eventually I may add some fruit in, but until I get over the hump, I’m keeping the insulin spikes as low as possible. I am having severe carb/sugar cravings, so I’ve been trying to eat more fat and/or protein. It seems to be helping, but I’m really hoping I come out of the fog soon! I know this lifestyle rocks and I just want it to work! Definitely had the low-carb flu this time, though…chills, got a bad cold that went away in a weekend…just felt feverish. Yuck! My energy level has been way more consistent the past few days, but like Mark said in the post, the brain is lagging behind! Hoping it will catch up soon!

    P.S. I’m also wondering if maybe b/c I have an autoimmune disease if that could be a factor for the hard time I’m having switching over.

  32. Jessica. You know that would be a great question to put in Robb Wolf’s podcast!!!!!

  33. It’s taken me about five months eating PB to finally figure out, at my activity level, about how many carbs I should eat. For a while I played around with less than 50 carbs a day, and I started to look really, well, frankly ripped for a 51 year old lady. But then at 108 lbs. I started to feel awful- weird dull headache feeling, NO energy, really tired- and I realized- Hey! You’re a horse [email protected] You burn through a lot of energy every day!! Eat more carbs!! So now I do, and I don’t get all anorexic about an apple or a banana or a yam, and I feel MUCH better, and I am learning to listen to my body, and eat butter and bacon and grass-fed beef and tons of veggies and even new things, like chicken liver and beef heart. So I am a very happy 51 year old paleo-camper, and I feel like a kid again. Or even better, because now I have my own money.

  34. You know, this sounds *exactly* like what happened to all the raw vegans. “After inital detox, your life will be amazing!” Except it wasn’t for most who tried the diet, and most quit. I wonder if the primal thing will suffer the same fate in 5-10 years. 🙁

    Joe, who is skeptical of all trendy lifestyles

    1. well except low carb, high fat has already been around a lot longer than five or ten years and is only becoming more and more accepted and there are more and more people who have been doing it for decades, whereas the span of the average raw vegan life is what, five minutes? And they all look like cadavers? THIS is a sustainable WOE, raw vegan is NOT. Im not talking specificly paleo though, generally low carb, high fat, moderate protein, so it really cant be considered “trendy” lol.

  35. In a low carb diet, more fat gets burned, of course.
    Fat is also used as storage to toxins. Maybe the fog and the low carb flu got to to with fat and toxins getting into the bloodstream and causing the fog.

    Just a thought I use when I feel foggy.

    Warm regards,


  36. when I first started going Primal..I severely cut my carbs. this led to not feeling well at all. I introduced carbs back in at a level of 100-150 grams complex carbs. I slowly reduced it to about 50-80 grams complex carbs. I now function quite well on a 30-60 level. I am quite active and do exercise for over an hour 3 times a week, and keep active for the rest of the week. it works well for me.

  37. For some people the symptoms could be a result of a candida (yeast) “die-off”. By cutting carbs and lowering blood glucose you’re restricting the candida of it’s food supply. On top of that, many of the PB foods are anti-fungal, killing more and intensifying symptoms.

    1. I was browsing through all the comments to see if anyone would make the link. This explains most of the so-called ‘low carb flu’ that affects many people new to a primal regime. Yes, the enzymes responsible for liberating ATP from fat need a while to increase their function, and yes, the nervous system does take several days to begin using ketones effectively but these two issues do not explain the majority of symptoms that people notice when they cut out most of their carbs.

      They are, however, starving yeast and IF they have a yeast issue (many do) they they are likely to suffer from a wave of fungal toxins such as acetaldehyde that come with such a die-off reaction. Doing it slower and adding insoluble fibre can help.

    2. This makes sense to me. Yeast overgrowth can be very tenacious. Kombucha and lacto-fermented veggies can be very helpful, much more effective than probiotic capsules, in my experience.

      1. I will try some Kombucha right now and kick up my intake of Olive leaf extract and silver. That may help me pull out of it.

  38. I had a little trouble kicking the caffeine when I first started a little over a year ago. A couple of days with a mild headache, then I was good to go. However, I haven’t had the big changes that many others have had. I haven’t lost more than a couple of pounds, and just can’t get rid of the fat over my abs. I’m a bit frustrated and am not sure what I’m doing wrong. Could be that my carbs are still a bit too high. Can’t seem to kick the craving for dark chocolate that still hits every afternoon!

    1. Greetings,

      I realize this post is old but I felt compelled to reply. I had intense chocolate, nuts and butter cravings early on my primal journey.

      I suggest taking a magnesium glycinate supplement as that could certainly be the cause of your cravings as both as very high in that essential mineral. I take a good 400-500mg sometimes upwards of 750mg and even 1g on high workout days.

      Perhaps you should try it and see how you feel. Fact: most of us are severely deficient in magnesium.

      Cheers and best of luck!

  39. I had bad withdrawal symptoms when I started the Primal lifestyle, but I was a total sugar addict. I didn’t really have mental fog though, but I did have trouble in the gym for about a week, which has passed.

  40. I was in a brain fog for years with high carb diet. Somewhere between week 5 and week 6 of eating paelo the fog lifted. I can think again!!

  41. I’ve noticed several things in the few weeks I’ve been at this seriously. One is that I’m more sensitive to mineral intake. There’s way more salt in the animal stuff I’ve been eating and I have to be sure to get my potassium. Same with high calcium — have to make sure to get my magnesium. Another is that I can’t slack on protein without paying a price, either. All of those help brain fog and I can see that balancing will be a learning process.

    Another aspect of this shift is that I won’t have the high carb diet cravings, highs and crashes, but if I’m unusually active, I’ll bonk! Happened the other day and the only reason I recognized it as such is that I used to (when much younger and fitter) do distance running and cycling. When you bonk, you don’t feel hungry. You just suddenly run out of gas, mentally and physically. As soon as I recognized it, I ate something and was fine.

    All that said, and fear of fat and other newbie anxieties taken into account, I don’t think I’ll ever willingly go back to high carb eating just because it is so damn great not to feel so bloated and strung out all the time.

    I want to go read up on high fat diets as epilepsy treatment. Want to see what they say about your brain on high fat/low carb in those studies.

    1. The guest blog comments a week or so back talks about this. In some small studies in children over here (UK) there was a big decrease in seizures on a low carb high fat regime.

  42. i made the switch very gradually, over YEARS, so no low carb flu. but i’ll tell ya, cutting out my BAD (5 cups a day) coffee habit last month was BRUTAL withdrawal. the headaches and brain fog!it’s nice to feel calmer now…though i also liked being sorta amped on caffeine and i don’t think it was such a bad habit. something about the pain of quitting makes me want to not start up again. our bodies get used to a certain chemical balance and adjustment certainly can be tricky.

  43. I’ve been playing with low carb for several years. The first time, I went strict Atkins induction all the way with the hope it would allow me to lose weight without too much suffering. Before that, I was in the habit of drinking ‘healthy’ fruit juice all day so the second through fourth days of induction where accompanied by very mild fatigue but also a truly unholy intense constant craving for fruit juice. One day at work, I caught myself just before my hand actually reached out and stole a coworker’s cranberry juice and chugged it! At about day 5, the cravings started to subside and then at day 6, I felt suddenly wonderfully great and energetic with minimal cravings. I think for some, it may be easier on the body to go slowly, but for me, I think the best was that I got through those cravings as fast as possible as they were torture! From there, it was fairly easy sailing and I was strict and loyal for 8 months or so, and then after that, I only occasionally cheated. I found that small amounts of fruits did not trigger any cravings and that the most important was I ate low carb at dinner. Then later, I lost my job and was forced to eat many of my meals at my parents house (super carby). I was depressed and gained a lot of weight. Later, I got another job and then read the book called Good Calories Bad Calories, which scared me straight! Perhaps since I had even when cheating tried to stay more away from carbs, the transition this time was quick with barely any cravings and no fatigue. Although interestingly, this time, perhaps due to also doing weightlifting, I actually gained a few pounds right away on low carb, and then lost it again plus more. Measurement around the waist showed I was slowly losing fat there the whole time though. I am now mostly primal but am not yet convinced that salt is a big deal to worry about (delving into the research just has not given me reason to fear salt in any way)and I still consume some diary, especially cream and butter. I try to stay away from lowcarb ‘fake’ foods, but once in a while, I will enjoy some lowcarb icecream. I am very observant of any carb cravings and I now know if I experience any carb cravings, then I have eaten too many carbs. I also try to keep most if not all carbs eaten to be healthy carbs like fruit and veggies, not antinutrient grains or other potential poisons. This seems to work for me. I have heard from many other females who say at some point after a long time on lowcarb, they began to feel tired and rundown. I can only guess why, and it does seem there are more women than men on this boat, but I think for some people, carefykkt uping the intake of HEALTHY carbs may be needed at some point. For myself, I will cross that bridge if I get to it, but so far, I sleep much better and need less sleep, I am stronger and more energetic, and I really enjoy my meals. I have also converted 2 others who have their own very encouraging lowcarb stories.

    1. Yep, read Taubes if you really want to understand why you are going Primal and why you should stay Primal, forever.

      I won’t EVER forget reading that book.

  44. Wow – what a great response.

    As for the 2 week time frame, yeah – it pretty much was that for me. However, I did do the crash and burn method – no sugars for 2 weeks…. since we started off with south beach. Which phase one use to be pretty much primal / low carb. I’ve noticed that has changed, in his newer books.

    Anyway – after that – we found MDA and we added some more variety in veggies which I think helped a lot. And, honestly cooking/eating primal is a LOT easier than SB/carb counting.

    Mostly it takes time – and like everyone else has said – you need to listen to your body.

    Also, I think it depends on how you approach things. I’m a all or nothing type of person. While it may not be the best approach – it works for me. I noticed some people like to count, others like to go slowly into primal. The thing is to figure out how you do things normally — and then make primal work for you with your normal style of doing things.

    good luck… hopefully it will work out as well for you as it has for us.


  45. Hi Mark,

    In the German Ketokenic Diet booklet aimed at cancer patients on how to use diet as a treatment, it is mentioned that it may take some days for the brain to effectively swap from using glucose into using ketone bodies for energy.

    In that sense it is not recommended to swap straight into a very low-carb regime, but to instead aim at daily 50g carb intake for a week or two before going lower.

    The whole booklet can be found here in English:


  46. I have been primal for 4 months. 51 male went from 23 PBF to under 14. Lost 20 lbs, over 4 inches in waist. Awesome health improvements. When I began, I had a low grade headache for 2 weeks. If I excercised, it got worse. After two weeks, fog cleared and began working out. Now Im in the best shape in my life and I was a marathon guy and moderate athalete all my life. Hang in there… your body will learn how to use good food just as it was designed!!

  47. Just finished my first week of Primal. My main “flu” symptom has been headaches, all day long for about three days, now off-and-on. They aren’t debilitating, just annoying.I haven’t noticed any big change to my energy level, but cravings and roller-coaster blood sugar subsided almost immediately. I’ve been pretty much at 50-80 carbs a day. Next goal is to try to stay under 50. In my first week I lost 5 lb., probably mostly water but encouraging nonetheless. I also feel less puffy, but it’s more of a subjective feeling, not a measurable thing.

  48. I would like to add another possible cause of low carb flu. The new Atkins book says that there is evidence that switching to a lower carb lifestyle can have a diuretic effect. This is part of the reason people can lose so much weight the first week. They are now suggesting having a cup of bouillon to help with the symptoms.

    1. I would think salt water is better for you than boullion cubes if thats what you meant. They have MSG (and who knows what else) in them, and if you are sensitive to MSG, that can cause migraines. I had an adrenal problem for years which caused water to just run through me without hydrating me, and my doctor recommended salt water with unprocessed sea salt or pink Himalayan salt. You should pay about 10 bucks or the like for a bag or else you aren’t getting the real stuff

      1. only really really CHEAP bullion cubes have msg in them these days, read labels. And bullion tastes better heh.

  49. Could these few people who suffer with the “low carb flu” just have a metabolic-type of a high carb eater?

    1. I too wonder about this. I know Sisson doesn’t subscribe to the different metabolic type theories, but from my own personal experiences, I’m starting to. Some people handle carbs just fine, gives them energy, and doesn’t make them gain weight. For them, weight loss just comes from portion control. Me on the other hand, I get fat from carbs. Too many makes me feel like crap, etc.

      1. it would be interesting to have all those who suffer badly from the switch to low carb on a test for their MT, maybe they would all (or mostly) show they were primarily carb eaters. That would be some decent proof.

        I don’t know either way, but it is at least possible.

        1. obviously there is genetic variance depending on the climate our genes evolved in. The obvious example of this is the Eskimo who eat almost exclusively fat and protein. Conversely, if you lived tropical, you’d probably be eating pineapple and bananas all day long. I would imagine that there is a wide variance among modern humans on carb amounts that our bodies can handle depending on what predominant genes got passed along.

  50. Two interesting things that can influence the low-carb flu that have been mentioned at coolingInflamation and Hyperlipid both actually have to do with your gut flora.

    1:FIAF ( at Hyperlipid, which in a nutshell is your gut flora if carb adjusted will scream at your brain when you change your diet and can make you feel pretty bad while adjusting.


    2: Gut biofilms ( covered at coolinginflamation. Where bad gut flora or carb adjusted flora can form films that hide themselves from your immune system and tie up metal cations (usually mg and calcium but in autism cases heavy/toxic metals too) and mess with nutrient absorption (because its literally a barrier between you intestine wall and nutrients and it tries to bind things like mg and calcium to itself instead of you getting to use it).

    when switching to a diet like paleo/primal during the adjustment period it can suddenly start breaking down the biofilms and adjust the ratio of your gut flora, which can mean you get the shock of whatever is making up that biofilm, and the bad bacteria die off all at once, in addition to whatever signals the bacteria send to your brain (intresting discussions linked here at paleo hacks

    Funnily enough a bunch of old school cure alls and some of the new school medicines as well as a paleo diet are all things that attack biofilms and bad gut flora ratios/carb loving bacteriums. (AVC, Pre and Probiotics, Fermented foods, antibiotics(only attack the bacteria outside the biofilms so temporary relive of symptoms), pectin/fruit fibers, spices like tumeric, starving carb reliant bacteria with a high protein/fat diet)

  51. After going primal (in February), I suffered low carb flu for about a week. But then for a couple months I’d wake up some days feeling great, some days feeling sluggish and achy. I finally connected the sluggish days with high dairy intake the day before.

    I’ve never had an issues with dairy, so this has surprised me. My thought is that in the past, my body was so out-of-whack due to high carb intake that the affects of dairy was lost in the noise.

    I am now experimenting with types/quantity of dairy to see if I can add back some cheese, which I miss. But thought I’d mention it as a possible affect people might want to be aware of.

  52. I havent really suffered from the ‘carb flu” mentally or physically. Apart from my first long bike ride shortly after starting, I seem to have plenty of energy. I’ve only changed to a primal lifestyle recently and think that rather than “carb flu” I suffer from “carb psychosis”. I can’t stop thinking about bread, sandwiches, pasta, rice etc. I think this will pass with time. In an effort to take the focus away from this psychosis, I started my own blog,, so that I could document my journey and particularly to refocus on creating healthy meals and alternatives in line with the primal blueprint while fooling my brain to think I am eating these things my subconscious can’t seem to let go of.

  53. I can confirm that it goes away after 2-3 weeks. Now after a few months I don´t have it anymore even if I eat an almost zero carb meal with lots of protein and fat.

    I had a relatively long “binge” where I eat a lot of sugar in 2-3 weeks after being primal for 3 months. After the binge the first few days were again harder but just a few days and not a few weeks. So 3 months primal, then 3 weeks high-carb didn´t reset my metabolism completely to high-carb but I felt a change when I started being primal again.

  54. The post by Robert says alot about the causes of this carb flu. Another common issue along this line might be what is known as the “herxheimer reaction”. This happens anytime you have yeast overgrowth and you start starving the yeast by cutting out sugars/carbs. There are 79 known toxins released from yeast when it starts to die. This may make you feel very foggy,tired and achy. This could be some explanation for what people might think is some sort of carb w/d when it’s actually the release of toxins by the overgrowing candida in the gut and colon.

  55. Grains and dairy are very mucus forming and when eating a lot of these foods one will store a lot of mucus in the body. When people stop eating dairy and grains and start eating paleo the body sarts to unload all that extra mucus. Hence, the cold or flu symptoms.

    1. My son has Aspergers syndrome, and in my research, I found out that in autistic children, or anyone with any form of leaky gut, gluten and casein, (the proteins in wheat and dairy) pass through the gut wall and enter the blood stream. From there, they pass through the blood-brain barrier into the brain and act like Opiates. I’m betting that a lot of us have this problem and don’t even know it. Never tried opium, but I would guess the withdrawl would not be pleasant.

  56. Get those vitamins into your diet…vitamins that are capsules, not “rocks”,(tablets), and quality Omega 3 oils…they do make a difference.

  57. I’m sure feeling it. I quit cold turkey because I know myself and if I don’t do this quick, I’m just gonna suffer and stop trying. This is my second day of PB, and it’s only 6:30 in the evening and I’m falling asleep. I also just ate another small square of dark chocolate (had one at 3:30pm) to help kill a sugar craving. However, I’ve only had two meals today and I feel healthy and full. I’m very happy about that where as before I needed to eat every two hours! So, I’ll just keep slugging through this as best I can.

    1. That’s not low carb flu, that’s not eating enough. Read the comments, this is something that hits people after about a week.
      If you don’t like the idea of adding more fat to your cooking then add coconut milk (no not light fer christ’s sake) and buy some almonds to nibble on between meals.
      You might think that I’m trying to sabotage your weight loss but I just want you to be able to live on PB, not just diet on it.

  58. I think I’m one of the people who went from lotso sugar to none and felt great… lucky me! I came right off of a vegan diet (was only vegan for a month), during which I ate tons of grains and sugar, had NO energy and felt close to death (mostly kidding). Anyway, the primal blueprint perked me (and my abs) right up fast! It’s been a month, i’ve lost 8 pounds, and my “sugar blues”/melancholy is G-O-N-E. thank you PB!!

  59. What kind of protein do you carry with you? I always have nuts and cranberries, but sometimes don’t feel like eating them.

  60. In my twenties (I’m now 67) I figured out I was hypoglycemic. Since then I have had to eat every 3 – 4 hours or not function, especially the brain,and I get clumsy. I have eaten mostly low carb, no junk food, since then, but eat and crave bread. Before being on this site, I thought whole grain was healthy. Is this chronic carb flu?

  61. My symptoms were mostly a thick mental fog for about a week. I just stuck with it and increased my fat intake, which helped some, not a lot. I also was scattered mentally, especially my short term memory–I’d be mid sentence and totally forget what I was going to say.

    I had been quite lethargic off and on before and could never pinpoint why. That’s gone now, of course. I have more energy than I know what to do with!

    As of now, my mental function is better than ever now, along with my energy levels and general health. Several other issues that I’d been trying to resolve disappeared and I truly feel a million times better than I ever have.

    1. My brain felt like there was a ‘satellite delay’ between having a thought and the words coming out of my mouth – almost like I was thinking & speaking in slow motion.

      9 months later and brain is all back to top speed and wonderfully so first thing in the morning and even after lunch, although I can lose it slightly if I don’t get enough sleep and I eat too much fruit.

      Day 7-9 I sweated constantly, just like when you have the flu – I was boiling. Guess my fat burning mode kicked in and the body got a bit of a shock!

  62. I’m feeling these exact symptoms right now! This is my second day consuming 68 grams of total carbs (about 1/3 polysaccharides, 2/3 di/monosaccharides). A little bit of regular coffee is helping, along with adequate b-vitamins.ct symptoms now

  63. I spent a year+ on Atkins and another year mostly primal so don’t remember carb flu that well, but I think this will help. From time to time I get the “blues” a slight depression and lack of energy without any real cause.
    I eat an avocado. I always feel better within 30 minutes!

  64. I am very new to primal eating, I just started reading the book this week. But as a previous carb addicted vegetarian, I have already made a lot of changes in my diet these past few days. I have been experiencing really bad nausea throughout the day. Waves of it come and go, in the afternoons and at night before bed. I feel better after eating a little chicken and have been trying to resist the urge to snack on a piece of dry toast! Any suggestions/experience with horrible nausea?

  65. Hi, I can’t seem to quench my thirst. Help. I am a few weeks into Primal and am losing weitht, too. Yahoo.

  66. I’m avidly reading all these suggestions, but are there any peri-menopausal women out there who started Primal and promptly started getting hot flashes? any advice? I’m slowly getting rid of the “low carb flu” after 4 weeks, NO cravings for carbs, losing weight nicely. Helped by being off sugar for a year which was a gentle weaning process and lost 10kg sloooowly! Thanks to David Gillespie’s book “Sweet Poison”, then I read Gary Taubes books and here I am going Primal.

    1. Hi Julie – yes I sweated like crazy start of 2nd week – had to stand outside the hairdresers in Jan in freezing temps to cool off – and I am normally a really cold person. The sweating only lasted a few days though – it started when I’d eaten coconut milk (with coco powder mixed in!) and I think it was the combination of high fat and low carbs that freaked my body out.

      It prob took me about 3-4 months to start to feel how I do now in terms of energy (I’m 9 months in). And it varied. Some days I had way too much energy and had to run up stairs to burn it off. Others I was dragging myself up the stairs – with just no energy. Nowadays the energy is pretty stable, unless I’ve not got enough sleep.

      It changes gradually and you tend not to notice it until one day you suddenly realise you don’t feel like you used to and you haven’t done for ages – you just hadn’t noticed. I think just get on with life and don’t focus too much on it. I may only have lost 8lbs, but I’m 2 dress sizes smaller and still falling – but that’s taken 9 months. It’s not a race and so don’t think about competing with these guys who just seem to lose it in a matter of days! Just remember that getting there slowly is still getting there.

  67. I honestly felt like I had the flu, full on, feverish, ached a bit, head hurt – set on a day after I began, but is was gone within 18 hours

  68. I’m into my third week of trying the PB lifestyle. I am a lifelong vegetarian so the changes have been pretty drastic for me. Prior to trying PB, I did make some changes to my diet by slowly decreasing my grain intake and introducing fish to my diet. I also quit dairy cold turkey when I started PB.

    I do not eat eggs, poultry or red meat, so my PB style consists mainly of fish and seafood and nuts (which I never ate before because of the high calories). Can I just say that I NEVER FELT SO AWFUL? The first week after about 3 or 4 days into it I had diarrhea. From the second week on the diarrhea stopped but now I have a severe case of constipation and not even laxatives do the job. I am so bloated I feel like I’m about 12 months pregnant (I know that is not possible, but I just wanted to illustrate how bloated and heavy I feel) and every time I eat or drink something my stomach balloons up. When I wake up, my face is all swollen and puffy. I run out of energy very quickly though some days I do have a little more energy. I’ve been tracking my food intake on and my diet is about 60% fat, 23% carbs and 17% protein, give or take some. I try to keep my carb intake to below 100g, but given my meat limitations I find my carb intake stays at about 120-130 grams. Need to work on that although my carb intake consists strictly of vegetables and berries. I am definitely eating enough as I do not go hungry. As a matter of fact, I fear that I am taking in way too many calories- I always end up at about 2000 calories and up which is way more than I am used to consuming (I’m supposed to be at around 1600 or so for weight loss). I don’t eat that much but I find that the fat (mainly consisting of olive oil in cooking and avocado) and the nuts really elevate the calories even though I don’t eat that much in terms of volume.

    I also have a constant buzzing in my head. That is not really the right description, but it is not a headache either. It’s more like a weird lightheaded/dizzy feeling that one would normally feel when hungover.

    Overall, I just really don’t feel very well aside from the sinuses that cleared up after I quit dairy. I think if the bloating, constipation and puffiness would go away, I could really adopt this lifestyle as I really don’t miss the grains so much. I do get hungry quite often and do get sweet cravings at night so I snack on nuts and berries. Another thing is that I find breakfast options quite difficult and end up eating a lot of veggies for breakfast (hence the high carbs). I tried eating eggs for about a week but my body completely rejected it. I started getting so much mucus and my nose was constantly running. I quit the eggs and the mucus cleared up.

    I am thinking that perhaps my body is taking longer to adjust because I have been a vegetarian most of my life and it’s been quite a shock to the system to handle so much protein even though I had slowly introduced fish to my diet prior to PB.

    I am going to stick with this for a while as I think the grain elimination does agree with my body (despite the bloating lost about 2 lbs in these three weeks), just the protein overload is a bit much for the system. I am thinking of reintroducing beans to my diet especially as breakfast options are so limited for me. And no, I will not eat red meat (pork or beef) or poultry not because of ethical issues, but simply because I can’t stand the taste (which is why I have been a vegetarian since I was 8 years old) and my body would go into convulsions if I forced myself to eat them.

    Has anyone had similar issues with the bloating and constipation and if so, how long did it take until you felt better? Anything I can do to alleviate the symptoms in the meantime? Any helpful suggestions would be appreciated!

    1. Lulu, I’m super bloated too, puffy face, etc. It’s been about four days since I’ve been eating very low carb Paleo. I’ve done this before though, and it did go away, but it’s really bad this time. I don’t have constipation, as I’m taking loads of magnesium. I’m also taking stuff to kill candida, so that may be making my symptoms worse. When I was younger, whenever I went low-carb, I’d immediately lose a huge amount of water weight. Not anymore. It seems to take a lot longer before the diuretic effect kicks in for me now. It’s annoying. Are you doing any better now?

      1. Hi Robin. I’m sorry to hear you are having the bloating and the swelling as well- not fun! I’m at the end of my fourth week and I did start feeling much better toward the beginning of the fourth week. The swelling and the bloating went down quite a bit and my stomach is back to normal level. I don’t have constipation as much anymore although I do have the intermittent attacks of diarrhea still. Magnesium supplements only started working after about 2 weeks or so of taking them.

        I still have very low energy all the time and I am still hungry all the time. But I still feel encouraged now with the swelling and bloating gone. And despite all this and the tremendously high calorie levels for me I still somehow managed to lose another pound this week- probably just the water from the bloating.

        Hang in there Robin, I’m sure you will start to feel better soon!

  69. The day after I wrote that post, I started feeling way better and felt increasingly fantastic all the way up until… christmas vacation 🙁 where of course i ended up eating some things i wouldn’t normally. now i am back to square one. it’s my third day of all paleo eating and i still feel like doodoo: major cravings, fatigued, bloated, etc. i can see the inflammation in my skin and my dull, bloodshot eyes. i only started eating poorly around the 29th (and by “poorly” i mean exquisite gourmet food at the finest restaurants). It’s crazy how 3 and a half days of eating fairly “normal” amounts of sugar and grains will do me in this much. it makes me wonder if i’m just becoming a hypochondriac or orthorexic. You still around Lulu?

  70. This explains so much. I’ve felt a little run down since I started this, but I’m determined to go for the full 30 days to test out PB. Carb Flu…

  71. add me to to roll call of carb flu sufferers. day 19 of whole30, and struggling mightily with thirst, nausea and fatigue. Luckily, the brain and mood still seem to be ok. I’m hanging on for my 30 days, but have no benefits yet, and still feel crappy. I’ve been told you just have to hang on, so I am trying, but it’s rough when you feel awful.

  72. I started eating primal at the beginning of December. I didn’t have any troubles until about 10days ago when I started experiencing lots of confusion, intolerance to cold, extreme exhaustion, eyes burning, itchy skin, & abdominal pain. Are these normal effects of going primal? I must note that I had a gradual change and haven’t completely gotten rid of all grains yet.

    1. Hi Mindy, you definitely aren’t alone with those symptoms. I also started at the beginning of December but went full-on primal. All my food was organic and all my meats organic and grass-fed. I even swapped over to raw milk. I was eating about 70g protein, 20g carbs and about 130g fat (those Korg calculation tables at the end of the PB book were very handy) – all monitored by fitday, as I had no idea what foods contained. I gave up coffee and tea and replaced fruit with vegetables. Initially, I struggled with the fat concept but food actually tasted so good with it that this was quickly overcome. After a week, my 3 years of bloating and stomach pain disappeared and I was ecstatic. I had about 4kgs to lose and lost most of that in the first 3 weeks.

      However, after that first week, I started to experience the symptoms you’ve described. I would go from shivering to sweating (in a tropical climate), was so tired I couldn’t get out of bed, my eyes were constantly red and burning, I had a head-splitting headache that kept me in bed for a week (thought I was dying), alternating diarrhoea and constipation, always thirsty and my joints were so sore, I felt like I was 110. When I did go to the gym, I had no energy after 5mins of body-weight training and would break out in a cold, clammy sweat and want to throw up. My perfect skin broke out in red rashes and dots and I developed a sensitivity to anything I put on it. Eventually I discovered steaming, apple cider vinegar and sweet almond oil and this has helped my skin immensely. I also started started developing patches of psoriasis on my scalp. Three weeks in, I discovered that I was reacting to dairy and coconut milk and cut those out. Will try again in a month or 2 as the idea of not eating triple cream brie or my newly discovered full-fat organic yoghurt ever again is too depressing to contemplate. I also get these brutally intense, wall-climbing cravings for red wine (I used to drink a glass a day).

      As of about 2 weeks ago, my energy levels have finally picked up and are quite good. I’ve eased up on my gym routine and now incorporate walks on the beach – barefoot. My skin is getting better but still burns if I put anything on it other than oil and apple cider vinegar. My stomach is sometimes queasy but I now make my own bone broth and this is wonderful. I actually crave it. Every day I take a teaspoon of good quality cold liver oil (and 1 or 2 bowls of bone broth), and occasionally also take vitamin b and c. I recently celebrated 4 weeks alcohol free – with a glass of red wine! Given that lemons now taste sweet to me, the flavours in the grenache shiraz mourvedre were out of this world.

      It has been two months and, all in all, the experience has been totally horrid. However, before I started PB, almost everything I ate made me feel sick anyway, so I figured my stomach was in a bad way and wouldn’t heal without a fight. After doing quite a bit of research, I now recognise that these symptoms were simply healing/detox symptoms and my body was/is trying to rid itself of years of accumulated toxins. Admittedly, the severity of the symptoms may also have been lessened if I hadn’t adopted the full-on approach that I did. Interestingly, I didn’t previously eat junk food or sugar and ate healthily accordingly to CW!!! I’m probably not out of the woods yet but I’m well on the way. My stomach thanks me and I’m close to my optimal weight. I have a wardrobe full of clothes that now fit beautifully, I’m much leaner and feeling rather good about myself. I’m also more aware of chemicals and toxins and trying to live in a way that’s kinder to the environment. I’ve also found an amazing butcher (Grass Roots Urban Butchery in Vaucluse) that supplies me with meat, bones and trotters from grass-fed animals raised humanely. I also have no trouble sticking to this way of eating because the thought of going through those rotten symptoms again is the best deterrent. Interestingly, I’m also teaching myself to cook. Being a low-fat adherent for years, I never realised how good food can taste when you start adding fat and eating PB-properly.

      So stick with it Mindy – it’s worth it in the long run.

      p.s. my sister has also started PB and has lost 5kgs of post-baby weight in 5 weeks – with not a single side effect and tons of energy. I guess you can’t win ’em all.

  73. It seems I had the ca-flu for about 4 days after about 3 weeks of going primal. This was about the time I got into rhythm with carb levels. I dropped from 250 carbs pre-Primal, to about 135 the first few weeks, and now hit under a 100 regularly. But interestingly enough, once over the ca-flu I began dropping weight a lot more steadily and quickly. 6lbs in the last week. Feel great. Pushing the word out to family/friends. By the way, I’m from Oxnard CA but living in Guam.

  74. I didn’t get the carb-flu with Paleo diet until I went further with a zero-fruit regimen to get past the plateau and drop some more fat. And then it was pretty mild. A few weeks later I didn’t feel the mental sluggishness anymore.

  75. Just wanted to thank everyone for leaving their experiences and insights here. I’m a week into full on primal living (averaging 60g carbs a day) and the flu hit me like a ton of bricks yesterday!

    I’ve been forgetting little things (like my address), been groggy yet unable to sleep, living in a bit of a haze and, the cherry on top of it all, almost had an “accident” in the supermarket yesterday as my bowels decided it was “go” time without telling me. Can’t make this stuff up.

    I was pretty scared but feel SO much better now that I’m finding out that it will pass. I just hope its quicker than a couple weeks. Thanks all!

  76. Hi, I am 41 and I cut wheat out of my diet after reading the book “Wheat Belly” about 2 weeks ago. I noticed that my terrible bloating went away. Then my acupuncturist got me the Primal Blue print and I have really limited my Carb intake.
    I have lymphocytic Colitis and all of the info I have received has been counterintuitive to my problems. A nutritionist told me at one point that I would have to eat white bread, gravy and canned food for the rest of my life. SInce every person I have spoken to medically has told me that I should avoid basically every food group (they always contradict the last person I spoke with) I have had to figure things out by listening to my body. But I have not done so great. I never ate the white bread but I have chose to avoid red meats and sugar.
    After cutting out the majority of carbs in the past 2 weeks I began to notice Gall stones coming out. I have lost 6 pounds 191 to 185 in this two weeks which is awesome and is keeping me motivated, But I feel really miserable. I feel so achy and tired. Has anyone had an experience with anything like this? Or gone primal with microscopic colitis?
    Thanks, looking for encouragement and answers.

  77. To those of us coming to Primal/Paleo via the Specific Carbohydrate Diet or GAPS, this “low carb flu” is a familiar thing called detoxing, or die-off. Essentially, all the pathogenic bacteria in the gut that feed off extra sugars begin dying off, and this releases toxins into the system. Indeed, even a new secondary round of die-off a few weeks in is known and expected, due to the different types of bacteria. This is a necessary evil for most … it means that your “bacterial household” is resetting.

  78. I needed this today. Day two of eating primally and feeling a bit foggy. Hopefully it will subside quickly. It is not too bad…yet.

  79. Hey Everyone An observation possibly experiencing no carb flu?

    Full Day #1!
    This morning after my walk with dogs and breakfast of fried onions and eggs I picked up the kindle to finish reading about paleo and got sooo tired… I was sitting up in the chair unable to stay awake. Slept well last night. Lay down and couldn’t get warm
    hooded fleece, 3 animals curled up with me and a blanket, nothing worked. Got up, put on another layer and then started sneezing with a runny nose… (knew nothing about no carb flu at this point) This afternoon I broke a sweat driving in the car and after that the flu symptoms left. It’s 11pm and I’m still feeling full of energy. Holy Jumpins… Normally I’m toast after 8 or 9 pm… Was still out in the woods with the dogs till 9:30!
    no after supper bloating (had a few berries from the garden and woods as dessert)
    Sore tired feet that normally/commonly happened by this time of night haven’t happen – my feet aren’t swollen, my stomach doesn’t feel bloated and my eczema isn’t as bad as it was yesterday… All in my head… who cares!
    Thank you!

  80. Ohhhh. Now it makes sense. I didn’t know about the “flu” but I had been experiencing headaches, though I didn’t relate it to the diet. I was so happy with the way things were going that it wasn’t important. I was just surprised because I’d never gotten many headaches. I was one of the people for whom this wasn’t a big stretch, though big enough I guess, to get the “flu”. It’s gone now and the enormous benefits remain. I’ve always felt better on a high protein, low carb diet but was always swayed by the “certainty” of the benefits of brown rice as a staple. Now that I’m grain, legume, and dairy free I’m healthier than at any point in my life. I have energy to burn (at 63) and can go all day. My exercise regimen is now about half what it was with twice the benefits. You just can’t beat this! My weight has stabilized at 127 lb on a 5’4″ frame. I try not to talk about it too much but I always wind up extolling this diet’s virtues when asked why I look so good. I’ve turned the clock back 20 years, effortlessly. If your new, stick with it!

  81. Hi Mark, I know this is an extremely late reply to this particular article, but I was talking to a scientist the other day about low-carb diets, and he mentioned that they can cause a brain fog because of low B-Vitamins. B-vitamins are essential for neural function and development, and usually come from grains and the like. Perhaps supplementing them can help prevent or reduce this symptom?

    1. Hi Sophia, I’m no doctor, but I can assure you you can all the B vitamins you need from fruits, vegetables, nuts and meat sources. I’ve found that doctors will feed you the old USDA food pyramid crap. I don’t know if they are really that naive, or there is pressure from the big conglomerates who control all the grains to not say anything. If you look at, you will see you get plenty of B vitamins from non-grain or non-dairy sources.

  82. Hey All!
    I have really just dived into my PB lifestyle and am really enjoying eating and tasting foods differently.

    My question is simple: When you all reference “carbs” could you clarify whether you mean Carbs in general, veggies, rice, fruits, grains, or do you mean only good carbs, veggies and fruits?

    I am a novice, so any advice is welcome!

  83. I’m feeling a bit crunchy lately. My challenge is canker sores which I’ve had off and on my whole life. Haven’t had them for a while but eating primal seems to have brought them on.

    The primal thing appears to be working though I saw veins on my obliques today for the first time. Hopefully this is what I need to get through the last 5-10 pounds. For those cross-fitters out there I suggest you google Tacfit and plug into that it awesome.

    I think in today’s world full of junk it makes sense to count calories because how can you win if you don’t know the score?

  84. Aha! Day 4 for me. I had to turn back twice this morning on my way to work because of things I had forgotten. Other than the brain fog, I feel great.

  85. since the age of about 14 (now 18) i have experienced a constant heavy headedness/mental fog, aches, and general fatigue – i attribute that all to eating an extremely grain focused diet. after 2 days of the paleo diet, i felt great! now a week later, i definately have the “flu”. I know that if i can just bare with it i will feel better, 2 weeks of flu is better then a lifetime of being ill!

  86. Hmm soo jessica has been feeling shitty on the primal diet eh? Could it be the low carb flu? Or is it more likely that she feels so horrible because even though her diet is primal it consists of mostly cooked food

  87. I’ve been primal for two weeks now so I thought my experience with this might be worth sharing. I made the switch cold turkey, with the only “cheating” being a serving of yams and a couple of beers over two weeks.. oh and some accidental soybean oil (store-bought mayo..I’m learning). So far, I’ve had nothing even close to the “low-carb flu,” in fact my energy is way up and more importantly it’s consistent. I used to crash every single day at 3pm, but it hasn’t happened since I made the switch. For that fact alone I don’t think I’m ever going back.
    My only somewhat negative experience has been that I get a little sleepy for a few minutes following a higher-fat-than-I’m-used-to evening meal, but I think that’s normal and it fades quickly.. it certainly isn’t severe enough that I would call it a problem.
    As I said I’m a bit new to this, but I suspect that my fellow primal tyros who are having especially severe symptoms may be under-eating.. particularly not eating enough fat. I’ve noticed that it can be hard to overcome the “fat is evil” propaganda in my habits, even though I understand it intellectually. When I’m tempted to eat ultra-lean per my old habits I try to remember this analogy, paraphrased from Mark, “fat is the firewood keeping the house warm, protein is the beams holding the roof up. The beams will burn, but why would you want them to?”

  88. I’m having a really hard time getting past the carb flu. Within the first 3 days of giving up bread, rice, soy products, pizza or pasta, I start getting headaches, feel nauseated, anxious, bloated, bowels cramp like hell and I wake up in the middle of the night having dreamed of bread and craving it.

    As I push through to 2 weeks, I feel like a drug addict, always craving, seeking, and then the exhaustion and weariness gets so tough that I start missing days of work as I sleep 12+ hours.

    By the third week I feel like I am a broken human being. I grind my teeth just wanting a hit of bread or pizza. I feel angry all the time.

    After that third week I run out of steam and ability to cope, and go back to the 150g-200g of carbs I was eating every day before I heard of paleo and was losing weight despite it. But now something has become upset, changed, and my body reacts violently and gains 10 lbs in a month.

    So then I try again, fail within two weeks, and another 10lbs flies on. These are not muscle pounds, it’s all fat in the stomach area that has never accumulated like this before. It doesn’t matter how many eggs, meats, veggies I eat, unless I have 100+g of carbs, I constantly feel like nothing ever “satisfies”. I don’t feel hungry, but always feel like pacing as if I’m missing something still, subconsciously chasing it. Carb cravings are cavernous and haunting.

    I’m now 20lbs heavier and scared of Paleo. Before I ever tried paleo, I was losing 20 lbs a year just through gentle portion control. Now my body is so pissed off at my diet change attempts that I’m stuck at a plateau. Whatever I did to lose wait without drastic changes isn’t working like before. It’s been 2 months since my last paleo switch attempt and I haven’t gained nor lost a pound. I’m stuck.

    I’m so envious of friends who switched to paleo and their bodies changed magically, without any physical addiction-like withdrawals. I don’t know what to do except feel a lot of regret. I had a good thing going, a stress free relationship with food that was continuously improving, and then I pushed buttons that upset it all. It will probably take a half year to calm down, get my body to not be so reactionary, and then return to the gradual weight loss I had become so good at.

  89. I’m getting lost in all the comments… so I’ll just re-ask the obvious. Don’t beat me…

    I’m a fitness instructor. I teach 2-4 classes per day (upwards of 15 classes per week). Zumba, Tabata Bootcamps, spin. It is my business, so stopping this level of fitness is not an option for me. This is week 2 of Paleo/Primal and I’m dying. 75-100g carbs is not cutting it for me. Or do I need to wait it out? Help meeeeee…

    1. yes, increase carbs for lifestyle. bump them up (particularly after a classs). maybe start at 200 carbs a day on hard days and slowly lower it to where you want to be. remember the workouts you’re doing are high heart rate, so you need more carbs.

  90. I have gone very low carb this week after 3 weeks of cutting out all sugars, caffeine, alcohol and anything out of a packet with preserves.

    It was tough at the start, but now with the carb drop i feel yuk, headaches, flu like symptoms, & so tired.

    My husband who is a type 1 diabetic told me that I would go into ketosis if I gave up my beloved carbs and this was really dangerous, I know that he sometimes has to check for ketones in his blood.

    I have to pretend im feeling fine otherwise I am sure he would cook me up a pot of potatoes and make me eat them if he knew how ill I was feeling. I’ve really gone off eating and the thought of meat & vege makes me feel sick, today has been the worst.

    I am hoping this will pass and I will come out the other end. I’ve stopped exercising (no energy anyway). All I want to do is do nothing or sleep.

    The other thing I’ve noticed the last few days is my skin colour, I’ve always been a pasty, white, sick looking with dark circles around my eyes, now I have ‘colour’ in my face and don’t need a 44 gallon drum of concealer and makeup….wahooo!

  91. As my daughter and her boyfriend have most every imaginable sensitivity I looked into solutions and went Paleo earlier this year. 64 and started at 219#. Couldn’t jog a lick. Fog wasn’t too bad but couldn’t sleep for but a few hours at a time for a couple of weeks that eventually disappeared. Down to 184, did 13 mile run the other nite getting ready for numerous runs and half marathon. Have hit somewhat of a plateau and increasing carbs after long runs seems like a plausible remedy. I no longer experience soreness after heaving indoor cycling and my runs. Now my wife is interested and heading down the Paleo path. Work the plan and the plan will work.

  92. Started low carb – high fat diest 4 weeks ago. We went cold turkey.

    I had no such fly but my wife did. Go figure 🙂

    But it is passed and we feel just great. I just discovered the primal blueprint and this makes perfect sense. We will now complete these new eating habits with the rest of the PB principles. We live near a lake and hilly forest in Denmark, a perfect environment for daily hiking. I will include weight lifting as well. After dall, diet is 80% but I don’t want my muscles to be eaten by my brain either 🙂 (I am near ketogenic at the moment)

    1. Jeeze, I type like crap … reaed fly for flu, and diest for diet! Damned …

  93. Glad to read all of this – was starting to feel like I was going crazy. Have been a conscious, but relatively high carb vegan for a long time. Started out introducing some fish and other things, and now settled into a paleo scheme that works for me. But, since I truly stopped the grains, sugar and alcohol – whoa nelly. Tired, able to sleep like crazy (insomnia used to be a problem for me) but a few times have woken in the middle of the night with a SPLITTING headache and feeling really weird. Overall just pretty low key, achy, spacey.

    Hope it passes soon! Thanks for all the encouragement from everybody. It’s very helpful.


  94. I just started this way of eating 2 days ago. I want to start exercising but am confused as to what to eat before and after my workout. HELP!!

  95. Hey guys, nine days on my BP and I feel sooooo sick some days that I really do feel like quitting. The worst part is I suffer from General Anxiety Disorder and some days I can´t figure out if it´s my anxiety symptoms or the carb flu. I have a question. Has anybody experienced anxiety or if you had anxiety before did it become worse getting on a low carb diet? I´m just hoping it will pass soon because I´m loving it for so many reasons. Today was a bad day, feeling shaky, very tired, weak, brain fog, wierd stomach feelings, just feeling sick overall. I can´t tell if my anxiety is getting worse or if it´s my body having a carb detox or maybe both. Can anybody relate? Can anybody give me some tips? One more question. Have any of you anxiety sufferers found that this diet helped with your anxiety: some, a lot or nothing?

    1. Have you tried magnesium? Get in the form of glycinate or other chelated, not oxide. It may help calm you. Also, try some higher carb veggies, like butternut squash, or even 1/2 a sweet potato, with lots of butter.

      1. Thanks fot the tip. I do consume almost every day yams with lots and lots of butter (my favorite treat). I also consume quite a bit of cucumber, bell peppers, celery,a variety of seeds, including sunflower seeds, sesame seeds, and flaxseeds. Beside getting the magnesium from my food, do I need supplements? I guess I will give it a try and see what happens. Thanks again 😉

        1. Some people have low blood levels of magnesium and need to supplement. I take extra magnesium to help with migraines.

        2. Natural Calm is a great supplement for magnesium. My Dr. recommended it to me 4 years ago, and I still take it every night.

    2. Hi Lila, I have an anxiety disorder and most of my anxiety went away by simply adding fat (eggs and butter, mostly) to my diet. The anxiety isn’t completely gone yet, since I just started eliminating grains and sugars a couple days ago. I have a bit of anxiety at the moment, but it’s definitely not as panicky as it used to be. Your comment was about 4 months ago, how has your diet been going? Is the anxiety gone?

      1. Hi Brian. I honestly did not feel any differente from when I was eating my regular diet consisting of “healthy grains”, protein, fruit and vegetables and I avoided sugars and processed foods and fats. When I went primal 4 months ago I was happy to eat bacon again, eggs, butter and the rest, so delicious! But it hasn´t worked for me, I gained more weight. I guess I was over eating more than I needed of every macronutrient. My anxiety was the same, it did not change until I started taking magensium, Thanks to Cindy and Max, I started taking magnesium supplements and I felt immediately better . I can say my anxiety and panic attacks are almost none existent. I am so happy for that. Thanks Cindy and Max. Maybe you should try as well adding extra magnesium. I´m taking almost 1000mg a day. That is how deficient I was! I had a very stressfull period in my life, I guess that´s why. Stess depletes you from precious minerals. This I just learned. I felt like dying every day, not any more. I feel almost normal again. I guess the body takes time to heal too. I had severe to moderate anxiety for almost 5 years.

        Any way, I went back to my regular diet but I keep away from wheat as I discovered my adult acne disappeard as well, so happy about that too. I had never had clear skin until now! Also the bloating disappeared as well. All the moderate carbs I eat now are corn and beans, fruit and vegetables.(I stay away from most grains or I soak them if I will eat them) So all I´m doing now is being careful on portion size. They say you should eat until you feel satiety, but I was over eating too much (too much fat as well) So this didn´t work for me. I´ll just go to eating balanaced, healthy and in moderation. A little itbit of everything works for me (even some sweet treats 🙂 I´m, glad it´s working for you. We are all different and have different needs and reactions. I hope you well 🙂

  96. Where can I buy natural calm? Do I order ir onlime? I live in canada.

  97. OMG!There are people starving in the world – their children are dying because all the world’s resources are being used to produce food for the so called 1st world and we have the luxury of saying that we really don’t want to eat carbohydrates even if they are there and cheap in our supermarkets!! We should be ashamed of ourselves for letting this happen.

  98. I felt dreadful particularly on day 20. I thought I would be locked into candida die off for 10 years and never feel well again unless I went back on to fruit and/or chocolate but then suddenly today I woke early and not exhausted. I had had 3 pretty awful weeks of feeling like I had an ME virus, terribly tired, eyes hurting, eyes watering, slightly blocked nose despite never drinking milk which is what normally can cause it for me, and most of all tired, tired, tired as if there were a drip on my arm draining the energy from me or as if vampires had been in the night to drain my blood and energy away. I thought I must be catching a germ at some point.

    (No really weight lost in 3 weeks and I gave up everthing except my 3 meals a day and small potato at night – I still have brown rice and baked potato so not low carb but totally clean and no snacks and only drink water)

    Then today I feel okay.
    I might try stopping my brown rice with meals although for my psychological health which for me is most important of all carb seems to be needed. I will see how I feel today but I do want to lose 7 pounds a month and only lost about 1 pound, possibly 2 in 3 weeks so far despite giving up all fruit, dried fruit and chocolate (which was at least 500 if not 1000 calories at day on top of my normal food 4 weeks ago and earlier so it’s surprising I have not been losing lots of weight).

    1. You probably won’t read this but thank you for reminding me of the Candida die off effect. I am feeling pretty bad. My symptoms are the same. But I’m determined. I do have an emergency banana if I need it.

  99. Day 18, and I have been having the low carb flu for 14 days now.
    Today I nearly caved and the cake on the counter looked awfully good to me!! But i did`nt… Instead I went on here and I’m gratefull for reading all the comments

    Nothing will stop me now

    Thank you

  100. I am so going through this right now. I’ve been getting headaches, insomnia, and fatigue. I wasn’t too high carb like most Americans. More in the 200-300 range before paleo and most of it was from eating too many medjool dates (I kind of have an addiction to them). But I was nowhere near 500s. I also haven’t had sugars except occasional honey for over a year and very few grains before I started. I haven’t cut dairy and don’t think I will. I just have way less off it than I used to. I also get light headed 15 minutes into working out. But today I felt much better (aside form insomnia last night). I can’t wait for it to fully pass!

  101. For what it’s worth, I was lucky and my transition was painless. But I had banished sugar from my diet (I replaced it with stevia) several years before I’d even heard of primal-paleo and about six months before I went primal I’d changed over from wheat to ryebread (lower in carbs) so in effect I’d largely weaned my system off carbs.

  102. I realize this is an old article, but I am a little disappointed.
    I was hoping to find some tips on how to survive the low-carb flu without giving up and jumping the train. But it sounds like all I can do is have faith and tough it out?

    I realize I’ll feel better than ever once this passes. I’ve done it before, but my symptoms are notably worse than they were the first time.

    Right now I fee like going home and taking a nap. I expect I will feel like that a lot over the next week or two. Is that a good idea, or a bad idea?

  103. I actually had the “low carb flu” for only one day and maybe slightly less the next day. I would feel pretty ill (fever, fog-headed/dizzy) the first day (evening actually) and then some sort of combination of energetic and ~weird the next day. After that it’s goes better (I started paleo 2 times and both times it went like this, both times before I started paleo, I ate some kind of modified paleo, which could more be described as gluten-free).

  104. 3rd day in my Primal diet (95%), before that I was a fan-of-carb-person. Have a moderate active lifestyle almost throughout my entire life. This morning I woke up with full of energy (haven’t experience this kind of energy for quite some time), my body was certainly very happy with the diet. Started to feel the effects of eating primal. However, after consuming my breakfast which consists of 5 eggs with the mix of mushroom, bell pepper, onion and tomato, I am experiencing a slight headache and very low energy – lethargy right now. I guess my brain have not catch up with the diet yet. I love the energy level I felt this morning. Certainly gonna stick with the primal diet. Keep going!

  105. Wow.. So glad I found and read this thread.. Me too!!to most of it.. On about 3-4 week now and slowlycoming out if the fog! I dropped carbs totally.. But the symptoms.. My god.. Aches .. Dizzy.. Tired.. Can’t sleep.. The list goes on,,, you have all
    Inspired me to keep going although I have put on a few kgs.. I understand this can he normal???

  106. I don’t think I eat many carbs but I am not losing (and sort of gaining). Today I am starting. I need help. I weigh about 124 and want to get to about 115-118 lbs with less FAT. I am 5’5″ and am used to having a rocking body….of course I am 57 years old now so nothing is easy (in my 20s I weighed about 105). I had tried to track with MY FITNESS PAL but it became difficult b/c I do pick (need to stop that) and how on earth could I track all the stuff I put in my salad?
    I am quite confused… many carbs should I eat to be “primal?” There are carbs in vegetables so are you counting all of them? It’s easy to be over 50 grams of carbs just by eating veggies (no fruit). Further, I think I am eating too many calories because when I get super hungry I eat a TBSP or two of organic peanut butter. Plus I probably eat too much bacon and avocados. Can someone please tell me how to start? I am overwhelmed with all this info….
    Thanks in advance,

  107. I have been very low carb for two days. I am 64 and I just cannot seem to lose 10lbs of fat on my body. I exercise daily. I also am a group exercise instructor. Today I taught a high intensity spin. I felt “pins and needles” in my legs and then started to feel light headed. Thought I was going to pass out. But I didn’t. I don’t know if I can do this. Went home and ate frosting!!!!! My bones and muscles ache. What do you think?

  108. Thanks Mark!

    I did keto for about 35 days starting mid October through november and wow – I was impressed. I felt more emotionally stable and consistent with my energy than ever. I also made the most money I ever made in one month in my entire life and got the phone number of a girl that looks like Arwen in LOTR because I was so “the man” – unfortunately I didn’t get the date when I made the call to ask her out cuz I got scared and went off my keto eating to take the edge off and kinda geeked out on her when I made the call.

    But this showed me how keto is the way to go something worth sticking with for the long haul. I just started back on Christmas day after seeing Unbroken – great movie – and am now feeling that flu again and this is very helpful to remind me that I’ll get through this and hopefully get those dates with beautiful women after I’m on the other side of this and have restabilized.

  109. Hello! – I’m new to paleo, quitting grains and such forth. I’ve begun by reading the book “Grain Brain” by David Perlmutter and occasionally I’m reading stuff on here too. I guess my best bet would be to read the primal blueprint?
    Anyway since the 2nd of Feb Ive been reducing my grains (I’m already wheat free) so I’ve also cut out spelt. I did falter and had some home made popcorn and I’ve been eating a bit of quinoa. Is this ok when weaning off grain?
    I feel stupidly tired though, immense brain fog and can’t seem to stay awake without a coffee – is this normal for when you go off grain?

  110. My experience so far is I went cold turkey into the Primal eating lifestyle on 1/27/15. I could be better at the exercise part. I believe I have been excellent sticking to the plan, save for some craft beers as my indulgence. The weight has been dropping off with great haste. I started at 288 lbs and today, 3/13/15, I am down to 256 lbs. I feel good when I am healthy, but 2 weeks ago I was on vacation in sunny Florida getting my daily sun exposure and relaxation when all of a sudden I came down with a nasty stomach virus that put me out for two days. I recovered pretty quickly and was able to enjoy the rest of my vacation. Then three days ago, I started feeling a tickle in my throat which a day later turned into a full blown head cold with stomach and intestinal disruptions. The skin on my torso, front and back, is sensitive to the touch. I have stayed on the plan through both illnesses. Before going Primal, I would eat my way through sickness. It’s interesting to see me not eating much through these ailments. But I figured almost 2 months in, my body should be healthier and my immune system should be stronger. I have no plans on changing anything from the plan that has given me much success so far, but is this typical for people to still be getting sick like I have been?

  111. Hey everybody.

    I feel like death. When I look in the mirror i see two dark shadows and some sort of white, pale plate-thing staring back at me haha! Everything hurts.

    The reason being I was a total twat and transitioned into the “banana girl” diet. Yep. 3 months. Carbs >500 per day. The results? Terrible blood readings on all counts, insulin resistance and pancreatitis. I don’t know what came over me but CAN YOU IMAGINE the flu in my case………….and this is just day three.

    I don’t even…

    EIRGH. Good luck to all of you anyway! I cannot WAIT for this nightmare to end.

    Honestly it’s been the worst and most stressful time in my entire life…I’m not sure what the point of my comment is I guess I just want to say hello and that your posts are giving me faith that i can eventually get over all of this 🙁

  112. 82%fat14%protien4%carbs and keeping a meal under 8 or 10 carbs seems to help me also bcause my slow gut n gall no protien after 5pm as it spikes my glucose heavy on the fat and protien early then greens and other low carb veggies and fat therest of the day with small amounts of protien broth at night very occaissionally raw cream and some cherries. Which is yummy but even that gives me glucose issues if i eat more than 6 cherries. So my numbers (bp,glucose,cholesterol, skin and mood )are only goodwhen strictly cutting out dairy nuts grains sugar and fruit. It is hard because i love berries and have difficulty every time i break down and have more than a few . It will take years of strict adherence for me to reverse the nerve damage but the immediate return to normal of my blood gl. And bp was astounding as well as losing 46 lbs in the first 2 mos. and staying around 165 for the last 4 while adding some muscle …just need to eliminate a bit more body fat not weight .had some setbacks lately with dairy and prednisone for injury have sent my glucose up but only have gained a pound or two once off the pred things should bounce back this way of life is saving me

  113. Have any ‘flu’ sufferers had any symptoms beyond being tired and having brain fog? I’ve been feeling very strong sadness, and very intense anger.

    I’ve been eating paleo 18 months (no grains, fairly high fat) – and was fairly close to primal eating anyway. I never got the increased energy that many other paleo starters talk about and I realized that I still had lots of sugar cravings. I would generally respond by eating fruit. So I decided to limit my fruit intake to reduced my carbs. I’m on day 6. The sugar cravings for the first 3 days were pretty strong but have mostly gone away since then. Energy levels and mood were normal those first 3 days. On days 4-6 I was a bit tired and had a slight headache. But – my mood was totally off. I’ve been alternating between very sad and very angry.

    Anybody else have strong emotions like that as part of their ‘flu’?

  114. It might be too late to post, hopefully you still see it. I switched to low carb/keto a couple of weeks ago, and since i did i have been very depressed, passively suicidal infact. I have been on meds for a while but have not felt this low in a long time. Will this pass?

    1. It will probably pass but please get help if you continue to feel sad or depressed. Very best regards to you!