The Lowdown on Keto Side Effects: What’s Real, What’s Not, and What’s Helpful

Inline_Keto_Side_EffectsWith more people enthusiastic about the ketogenic diet comes more talk about potential adverse side effects. Upon closer examination, almost all of the complaints can be traced to a flawed approach. Granted, if you are coming to the game with significant metabolic damage from decades of carbohydrate dependency, or not paying attention to some common sense best practices, such as choosing healthy foods instead of blindly focusing on macros, you will likely struggle with something as stringent as keto.

Let’s cover some of the common keto complaints being bantered about these days, examine what’s really going on, and discuss strategy for how to avoid any adverse side effects to going keto.

Keto Flu

The keto flu refers to feelings of general malaise and even immune disturbances in association with dietary modification. Commonly cited symptoms include feeling lethargic (especially in the afternoon), feeling hot, feeling achy in joints and muscles, among other related sensations.

Here are eight important tips for avoiding the keto flu. Check out the full post for further details.

  1. Get sufficient omega-3s, from oily, cold water fish or supplementation.
  2. Consume an extra five grams (1 teaspoon) of sea salt or Himalayan pink salt per day when going keto.
  3. Consume foods rich in potassium and magnesium. Avocado is an excellent high fat, low carb source for both.
  4. Make an extra effort to hydrate strategically, especially around workouts.
  5. Consume more healthy, natural fats to replace the carbs you are cutting out.
  6. Consume MCT oil (from coconut oil or MCT oil supplements) to stimulate external ketone production.
  7. Move frequently and conduct cardio sessions at low heart rates.
  8. Try a gradual reduction in carbs if an abrubt reduction seems problematic or you experience keto flu symptoms.

Finally, wait it out. Certain folks who do everything by the book and follow every bit of good advice may still get a few symptoms of the keto flu. This usually comes in the initial three weeks of entering nutritional ketosis, and things get much better very quickly. Trust that your lull will pass and your energy will increase substantially—usually within a few days.

Keto Poop

Someone asked me this the other day on a podcast: What’s the deal with keto poop? A disconcerting number of people on keto diets appear to be having trouble with their poop—or lack thereof.

The biggest issue is that some people consider keto to be a free pass to skip the green stuff. Either that, or they assume “vegetable=carb” and avoid them. Without plants, it’s tough to eat enough fiber, especially the fermentable, prebiotic kind that sustains our gut bacteria. We don’t need bowel-rending quantities of fiber. We shouldn’t take pride in the ability to fill the toilet bowl with perfect coils of crucifer corpses. These are unnecessary at best and downright harmful at worst.

But we still have to feed our gut bacteria. We still have to poop. We don’t want to strain and come up empty. Humans are industrious apes; we like to produce, not work in vain.

What else is going on, besides the lack of fiber?

You may need more water. Going keto causes an initial reduction in fluid retention in cells throughout your body. Your digestive tract requires water to keep the fecal matter soft and moist. As you aspire to consume more fluid, be sure to add a pinch of salt to each cup of water you drink, and to sip steadily throughout the day instead of binge chugging. These measures will help you better absorb additional fluids instead of excrete them.

Take magnesium. Magnesium helps regulate gut motility, and magnesium deficiencies are a common cause of constipation. Magnesium needs tend to rise on keto as well. Some experts recommend taking 400 mg in supplemental magnesium per day when going keto.

Take resistant starch. A starch that acts like fiber, RS is one of the most potent prebiotic substances around. Raw potato starch is an easy, dependable source of RS. Start slow with a teaspoon into your smoothie or full-fat yogurt; work up to at least a tablespoon per day.

“Deflated” Muscles

When your glycogen stores are topped off and your muscles are full of water—each gram of glycogen is stored with 3-4 grams of water—they’re bigger. More pronounced. Fuller. Going keto, which depletes muscle glycogen and reduces fluid retention, can give your muscles a “flat” or “deflated” appearance.

You can accept it for the time being. As time goes on and your body calibrates itself to the new metabolic pathway, you won’t shed as much water. Your muscles will return to normal.

You can work carbs into your diet before, during, or after hard training sessions. Anything intense enough and long enough to burn through muscle glycogen allows carb consumption without knocking you out of ketosis.

You can try creatine. Creatine is also stored in the muscle alongside water, so it may increase muscle fullness. Creatine also has the benefit of increasing muscle phosphocreatine energy stores, which we use for quick movements and brief feats of strength.

Low Energy

Some people just won’t do as well as others on a ketogenic diet. In particular, high energy demand athletes often choose to consume more nutritious carbs than advised per keto guidelines. Females with metabolic damage from a history of yo-yo dieting, or thyroid or adrenal dysfunction, also report difficulty with prolonged carb restriction to promote keto.

Again, with an optimized approach, things might come out great for virtually everyone who tries keto. Realize that since going keto opens up an entirely new energy pathway without limiting your ability to access the previous pathway, low energy is actually a pretty rare complaint. If it crops up with you, here are some things to watch out for:

Chronic exercise patterns: Fat-based metabolisms are great for long, slow movement, quick bursts of speed with rest in between, and feats of explosive strength. In other words, making your way through the world, doing some strength training, going for hikes, playing with kids, running some sprints, and are all tenable on keto. Heavy CrossFit training or anything else that burns a lot of glycogen at a lot of workouts each week, however, might pose issues. Resolve this by either scaling back the training or eating some carbs before, during, or after your workouts.

Inadequate calories: Keto’s satiating qualities are a double-edged blade. They help us eat less and lose body fat without really even trying, but they can also sometimes lead us to eat too little. This can cause a reaction in your body to slow down metabolic function and make you feel generally less energetic at rest. One solution is to cycle periods of generally increased caloric intake, and increased intake of nutritious carbs by default. This suggestion is totally different from the suggestion to engage in purposeful carb refeeds, where you binge on nutrient-devoid carbs in the name of a cheat day. This is never advised for any reason.

Unrealistic expectations: If you’re five days into your keto experiment and about to give up because you yawned after lunch, have a little patience. Things take time to change.

Hair Loss

The diet’s going great, you’re dropping inches, you have good energy levels, increased clarity of mind, but every time you take a shower or brush your hair or join a gorilla grooming circle, you’re losing hair. What gives?

You’ve lost weight. By far the most common cause of unexplained hair loss is simply rapid weight loss or dietary change. This disrupts the normal growth and decline cycle of your hair follicles, shunting a greater proportion of them into the “rest” phase to be pushed out by incoming hairs. Even though you may see extra hair in the shower or on the brush, your actual hair thickness shouldn’t change much.

Check your thyroid. As I wrote in a previous post, certain incarnations of keto (high in omega-6, low in supportive nutrients like selenium and iodine) can lower T3 levels, and this can cause premature hair loss.

High Cholesterol

The doc hands over the printout.

Last week, he’d expressed major skepticism over your new diet. “Sure, you’re losing weight, but let’s see what it’s doing to your arteries.” Today, you already know. His smirk says it all.

“You’ve got high cholesterol.” He’s beaming. Why the hell is he so happy?

It’s a fairly common scene for new keto dieters. Aubrey Marcus recently referenced a highly-disturbing stat that 25% of physicians still equate consuming dietary cholesterol with increased blood cholesterol, an association that has been unequivocally refuted by recent science. But before you accept AHA-sanctioned diet advice, determine if there’s actually a problem.

Check your ratios. Total cholesterol/HDL ratio is a good indicator of how long LDL is hanging around in the blood and remains the best standard assessment of heart disease risk. Another good one is triglyceride/HDL ratio, which is a strong surrogate marker for insulin resistance. In both cases, lower is better. An ideal T/HDL ratio is 1:1. I’d say 2:1 is about as high as you want to go. An ideal TC/HDL ratio is 3.5:1 or lower.

Stop grazing. Allowing time to pass in between meals, or getting crazy and deciding to skip a meal or two, has been shown to improve cholesterol numbers.

Don’t gorge on fat. Remember that the best things happen when you’re consuming your own body fat. You don’t need to melt a stick of butter in your coffee every morning to keep your membership in the keto club.

Balance your fat. Saturated fat has received a terrible rap in the literature, but that doesn’t mean it’s the only fat you should consume. Look to the fatty acid ratios of ruminants like beef and lamb—or your own adipose tissue—for guidance. They have about equal amounts of saturated and monounsaturated fat with a small amount of PUFA. Mix up the butter and cream with olive oil and avocado oil.

Give it time. Your body’s still adjusting to the new energy pathway. Give it a few more weeks before you worry (and even then, don’t worry too much).

Those are six of the most commonly cited adverse side effects of going keto. As you can see, sometimes they’re real and you need to make changes, sometimes they’re a misinterpretation and you need to look more closely, and sometimes you just need to relax and let the process take care of itself.

Thanks for reading, everyone. Any thoughts to add on your transition to keto? Take care.

TAGS:  Keto, keto-popular

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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126 thoughts on “The Lowdown on Keto Side Effects: What’s Real, What’s Not, and What’s Helpful”

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  1. Good to know, thank you for the insight. Have a great Wednesday.

  2. “perfect coils of crucifer corpses.” My, how you can turn a phrase, Mark! Keep up the good work. Thanks for the laughs!

    1. I read that and cracked up as well. Then I read it again just for good measure and cracked up again.. Thanks for keeping it real Mark.

  3. I would love to hear your opinion on danger of getting kidney stones from ketosis. Thanks!

    1. I’d also like to know. After a few false starts I finally was able to get off grains and sugars and then ended up with a kidney stone that wouldn’t pass. In hindsight by that time I didn’t have much appetite and had probably slid into keto. That was an experience that I do not want to repeat. While my diet is fairly primal I’ve never achieved that level again because that kidney stone is always in the back of my mind

  4. I get terrible insomnia from going keto. Most of what I’ve read recommends increasing carb intake. I did that and I’m sleeping better. I guess keto isn’t for me. Oh well.

    1. I’m glad that worked for you, George, but I tried it when I was too enthusiastic with my intermittent fasting and couldn’t sleep longer than 1.5-3 hrs per night. The carbs did nothing for my sleep, unfortunately. I had been fasting for roughly 23 hrs, then eating one main meal at 1-2pm each day.That’s when the problems with severe insomnia started. As soon as I added several hrs to my eating window, making sure I had a moderate dinner each night, I started sleeping soundly again 🙂
      I’m so glad I experimented with ‘when’ to eat, not just ‘what’ to eat. My health and blood work has amazed my doctor since adopting a low carb diet. All the best!

      1. I eat my one meal at dinner so no probs with insomnia. I don’t sleep deeply if I am in fat burning weight loss mode so I reserve that for daytime.

        1. It’s amazing to find out what a difference it makes in meal timing, doesn’t it? I couldn’t believe the difference. It wasn’t hunger keeping me awake, but as you say being in fat burning mode. Add to that our cortisol levels rising in the wee hours and that combination was brutal for sleep.

          1. Wow, never thought about how this could impact sleep. I’m a light sleeper to begin with, and have had a few nights recently where I really couldn’t sleep (including last night) Looking back, those were days where my carb intake was extra low and really didn’t eat a whole lot…thinking I was just kind of buzzed from being in fat burning mode.

          2. For me, at least, it has nothing to do with carb intake; it only matters when I eat. I have to have a meal sometime between 6-8pm, preferably. Even if I’m having a steak and eggs with zero carbs, as long as I eat sometime after 6pm, I sleep well. 🙂 Best..

    2. Me too. I feel jacked all night. Still playing with different exercise, caffeine, supplement variables but I am shocked at how little is written about this. All I see is the standard sleep solutions (read, melatonin, tea) but this is not the same. Between the recent popularity of fasting and keto, I can’t believe more people aren’t having this problem.

      1. Have any of you tried essential oils for aiding in a good night sleep. Diffusing lavender, frankincense and vetiver is incredible. Make sure the oils are certified pure therapeutic grade, I recommend d?TERRA.

  5. Actually, the ‘Blue Zone’ populations and the last free roaming humans, do eat TONS of fiber and do poop a bunch. The fools, they need to go ‘keto’, get constipated and feel like crap (no pun intended) during a ‘break-in’ period!!

    1. Eddy T you’re so silly.  The folks in the blue zones have no wisdom and don’t know anything.  They eat mostly delicious carbs and very little meat, drink wine every day, live into their 90’s disease-free, and have great sex until the end.  You should go Keto…. for your health!  It’s a perfectly natural way of living (just don’t forget the expensive multi-vitamins and testosterone shots).  The anxiety, constipation, and low libido will all be worth it when you lift your shirt and take a selfie of your 6-pack abs in the mirror!  That’s the most important thing anyways.

      1. More steaks and red wine for the rest of us. You can have the carbs because I love being free from T2D and excess poundage (not to mention, fartage 😉

  6. Great article! Can you expand on the statement “One solution is to cycle periods of generally increased caloric intake, and increased intake of nutritious carbs by default.” I’ve never been a fan of cheat days as it really just didn’t feel right to me. I would like to learn more about what you are suggesting…Thank you!

    1. Sounds like he meant more of a eat more HEALTHY carbs day, not that you would eat a bunch of crap food which is the more common definition of a cheat day.

      1. That’s interesting because MY cheat day (I never had one, but I have fantasies about it) is eating some plantain or a small sweet potato. The foods I miss the most are considered real food, they are just carbs.

        1. I don’t recommend staying with the fantasy. In all cases, it’s a remnant of either neurological or emotional addiction.

          If anyone holds (romanticised) anticipation for a cheat day, it’s very plausible the cheat won’t work for them. It’s supposed to be a release valve, to liberate tension lodged throughout the week; but anticipation denotes unhealthy clinging to the punishment-reward axis in the brain.

          What that means is that you fall to the level of your mood swings, which all disdain change and frame the past habits as oh so sweet, instead of using healthy mental models like mindfulness or discipline or intuition to envelop each moment and their challenges.

          I guess this message is more general and not necessarily targeted to you, but that emotional addiction of clinging to a past “framing” is a pitfall I’ve seen many addicts sink into. It’s not pretty. That’s why they say you must synchronize your brain with the present moment, and listen to what it has to say. Next time you have a craving or fantasy, how about doing a breath exercise or mantra that pulls you out of the emotional swirl? I think it will make those moments of craving easier to bear.

          1. I never said I was going to give in to it, I know that would be a mistake for me. Trust me, I’ve pumbled my body for years and deprived myself of things that I wanted to eat, I know discipline. The fantasies are mostly passing. I don’t dwell on them. I am able to let it go due time, usually seconds.

          2. Alright. No allegation implied; the purpose of that response was to offer this timely chain of comments on cheat carbs and what not my thoughts, my experiences. The bigger the surge of new people that get on board, especially since Mark’s book, the more important it is to open a dialogue on mental perception as well as nutritional facts. Because, to be honest, you could be the most informed ketosis geek in the world and still be a carb junkie. With any change, the biggest shift is a mental one. Cheers on your journey!

          3. I totally agree with you there! Cheers to you too!

  7. My personal experience completely matches with these issues related to fitness intensity. When I first read Primal Blueprint 8 years ago, I dropped activity to short walks for first 4 weeks just to ease into it metabolically. Then, started going on 10 mile bike rides or 30 min walk/runs as my keto energy kicked up. The energy you have once you get over the hump is astounding. I didn’t have that much energy in high school and I was an athlete. I lost weight to below my senior year of HS and I didn’t think I had much weight I could lose to begin with. Not why I did it. Inevitably, I was all arrogant with primal energy and got into Crossfit. Within 2 months I was super strong and also super wasted, falling asleep on the mat. The regular (4-5 days a week) intense lifting broke my metabolism and crashed my testosterone (confirmed). Once I backed off again, I was careful not to overdue it.

  8. I wish you would just go back to your common sense primal blueprint. This keto “fad” just sounds like a recipe for disaster for people who will obsess on the details, or, as this article states, for people whose metabolisms are not suited for the “stringent” keto diet. There are no side effects from following a common sense “primal” diet/lifestyle. Why mess with a good thing?

    1. Yes. My side effect from keto is constantly falling of the wagon, and then losing results because i seem to gain fat super easy if i go off even for just a while and for me its too disheartening and then have to try to get back on. I’m still primal but its too easy for me to enjoy sweet potatoes pomegranates grapefruit apples. Etc. And maybe a but too much honey and butter on my keto bread to stay keto. i seem to start to get insomnia and anxiety and with my history of adrenal fatique it seeems folly to try…while still breastfeeding at least…but then i get all FOMO?…

      1. I would say don’t worry about missing out on keto while you are breast feeding! Relax, eat what feels right (but many try to cut down on the “foods” like keto bread) and enjoy this special time with your baby. Perhaps when you are done breast feeding you can look forward to trying strict keto to kick the sugar addiction.

    2. I think it is so awesome that Mark is so on top of the research and is always willing to try research backed dietary shifts to go to the next level. I have LOVED being in ketosis for long periods over the past (almost) two years and was very excited to read “The Keto Reset”. In my experience, ketosis feels like next level primal. I have completely eliminated the craving for sweets and enjoy healthy fats and vegetables in abundance. I can go very long periods without eating and maintain steady energy. In fact, my energy and mental clarity are through the roof. I haven’t experienced any of the side effects that others are mentioning here.

      What is great is that you get to do what feels right for you! This is what Mark (and many others) are excited about right now and I enjoy and appreciate all of the information he gives us, free of charge!

      1. judging from the many comments, you appear to be one of the lucky ones katie. but gwen has illustrated my point by trying to maintain ketosis while breastfeeding. a healthy diet is varied and nutrient-oriented. it may be true that ancestral humans were in a state of ketosis more often, but likely not for years at a time, and certainly not by design.

      2. Katie, I get those same results from 90/10 Primal. Apparently for some of us less is more, particularly with regard to women. I agree that we all need to recognize what is right for us as individuals versus hopping on every dietary bandwagon just because it works for someone else.

    3. It’s not right to mislead others by calling the ketogenic diet a “fad.” It’s been around since at least the early 1900’s and was used for those with epilepsy and diabetes and it’s now used by many in conjunction with cancer. Please do some research before saying things about it to dissuade people from trying it for themselves or their loved ones.

    4. I like keto a lot, I never got any of the “side effects,” perhaps because before I discovered keto I’d already gone a few months with zero grains or added sugars or processed foods, so I was probably already pretty fat-adapted before I went “strict”. I’ve been keto over a year, though with occasional cycling out of it, usually to allow social grace when out with friends at a restaurant or party. But always I can’t wait to get back to “my food,” and now on the verge of my 52nd birthday I’ve never felt healthier or in better fitness.

  9. I’ve been keto for over two years. I was mildly pre diabetic at the time. I started and keto seemed to fix it. Now despite no changes to my diet, my fasting blood sugar is over 100 and this morning it was 114. This is after many months of perfect blood sugar (85 or below). I’ve been sliding upwards for about 6 months. My AIC has actually gone down to 5.3. I am thin, about 120, fast 18-6 with one or two 24 hour fasts a week, go to the gym 4 or 5 times a week, plus I take a yoga class and garden. I eat a strict keto diet. What should I do now? Please help!

    1. One thing to try is get on one of the websites where you track food intake and it tells you want nutrients you are getting and what you might be low on. See if you are low on anything, this may or may not help but it will not hurt. When cutting out thing like potatoes and fruit, it is easy to get low on some vitamins or minerals and many people do not digest common cheap multivitamins well.

    2. What’s your sleep like?
      Gym 4-5 times a week and a yoga class. Hmm. Sounds like your burning it at both ends. Another poster did something similar and ended up burning out with low test.
      Similarly it sounds like your hormones could be effected.

      1. Hi again! I guess I should explain that I’m retired and I walk about four blocks with my gym buddies to the gym for a brief stint that is surely not leading to burn out. I sleep 7 to 8 hours a night without waking up. My hormones are in the right place according to my NP. Yoga is relaxing for me so I can’t see a problem with that and I love the gym too! I love to cook and I eat well. My HOMA-IR is in the right place and my NP is not worried about it. (She also eats Keto.) I would appreciate Mark commenting on HOMA-IR because this is something new to me. I’ve not heard anything about it before and would love to hear Mark’s opinion on what it is and how it works.

    3. You’ve gone overboard with everything and your body can’t handle the stress load. Try cutting back the gym to twice a week, eliminate IF altogether, at least for a while, and dump the strict keto. A 90/10 Primal diet that includes plenty of healthful calories for energy and wellbeing should eliminate pre-diabetes and keep weight at a normal level. Your obsession with the numbers likely isn’t helping either. Forget about all that and just LIVE. For many of us, moderation actually works much better than extremes.

    4. Same problem here. I’ve been low carb/keto for almost 3 years. At first my blood sugar was in the 90’s, but now it’s over 120. A1C reduced from 5.7 to 5.6.
      LC doctor measured insulin and reassured me that the important measure is HOMA-IR. Things are good as long as HOMA-IR is under 400. So the key is low insulin, preferably less than 5.
      For some reason GNG works overtime on keto. Need glucose for brain?

    5. Hey, some in the keto community, refer to it as physiological insulin resistance (glucose reserving). My blood sugar rose to 106 but my HbA1c dropped from 5.7 to 4.5. High cortisol levels will also effect sugar levels.

      1. Agreed. But what is the risk?
        There’s nothing good about high blood sugars.

        1. I guess it depends on what is considered high. Mine went up to 101 mg/dl but HbA1c dropped significantly, so I am not too concerned. But several points above that could present issues. One way to mitigate that would be to break out of kitosis every so often. Right?

          1. As you said, TT, high cortisol levels can also cause bg levels to rise. Unfortunately, some people tend to blame the keto first. At the end of the day, though, we all need to figure out what our bodies want. Some may want some extra carbs and some do best keeping carbs very low. Then there’s the zero carb group who goes for years in great health. We all need to figure out what works for us without bashing what works for others.

  10. Hi, good article! One question: what’s the source of your nutritional data on avocados? It’s my understanding that they are actually pretty low in magnesium. Good source of potassium, though.

    1. An avocado has 45 mg of magnesium and 750 mg of potassium, which is 12% and 18% of the daily recommended dosages (fwiw) respectively. So, yes, there’s a lot less magnesium in terms of mg, but it’s still a good amount percentage-wise.

  11. Your comment about crossfit not being ideal while in Ketosis, do you think the crossfit movement is distancing themselves from promoting Ketosis or Low Carb? When I was doing crossfit 2012-2015, crossfit and low carb (ketosis was gold standard) went hand in hand. The 3 gyms I went to all had 30-90 day low carb challenges (Paleo to Whole30). Intersting that you make this claim since one of the early adopters of crossfit, Robb Wolf (norcal fitness) was a student of Loren Cordain (founder of Paleo)….

  12. I love everything about keto, except my sleep isn’t as good, especially after the first 3 or 4 hours. I also find that during my ‘wakeful’ periods, my heart is beating quite a bit faster than it ought to. I am very careful about my mineral and water intake, but so far it hasn’t seemed to correct these issues. I’m hoping that a few more weeks doing a ‘keto reset’ and this will get better. Otherwise I’ll have to start investigating other things. Thyroid? High cortisol? We’ll see…
    Thanks for all your great advice Mark!

    1. Is what you are calling a “wakeful period” when you are sleeping but waking frequently? If that’s the case I would investigate whether or not you have undiagnosed sleep apnea. Two of the sytems are waking frequently and a racing heart upon waking.

      1. No, it’s more having a really good sleep for the first part of the night, and then waking up and not sleeping particularly well for the rest of the night. I feel more or less fine during the day though. Great even energy and clear mind is awesome. My resting heart rate is higher now, as is my heartrate on a treadmill with the same effort pre-keto. From what I’ve read, I expect this to get better within a couple of months. I know that plentiful hydration and minerals is important in minimizing this symptom.
        Thanks Michelle.

    2. Several others suggested moving meal times around to adjust to better sleep patterns

  13. Folks might be interested in this article from the 1930’s. V. Steffanson lived with the Inuit and ate an all meat diet with no harmful effects. When he got home, the medical establishment didn’t believe him, so he and another man ate an all meat diet for a year while they took blood samples and did regular exams. Fascinating stuff.


    1. I just read an article in a local publication about a Native Alaskan who decided to eat in the traditional way to see if he could improve his health. For example, he ate whale blubber, seal and seal fat, moose, and plants native to his village (of which there were few). He lost a ton of weight and now advocates for the return to traditional foods in Alaska.

  14. I did very low carb/intermittent fasting this past spring. I read all the good books, websites, etc. Ate lots of avocados, coconut oil, drank lots of water, took magnesium supplements, etc. Lost about 14 lbs. over 2 months – felt pretty good…UNTIL …I developed nasty acid reflux (which I didn’t have before), and wound up at the ER one night with a BP of 200/110 and feeling like I was going to have a heart attack. Part of it was due to low potassium, even tho I was doing everything “right”.

    The acid reflux did not go away (even with all the pills they gave me) until I quit low carb/intermittent fasting. I know 2 other women that were doing very low carb and also wound up with a bad case of acid reflux (one was my own FNP). Most people report GERD/Acid Reflux getting better – not worse. I am pretty bummed because this actually helped me lose weight and reduced overall joint pain. I did have an endoscopy after this episode (“normal”), and I have asked several doctors why this happens, but I get no answers. So, just wondering if anyone else has had this happen?

    1. Wow! I have never heard of this from low-carb/keto but I hope you get some answers. What is your diet like now?

      1. Hi Carla – I’ve been still trying to stay away from bread/pasta for the most part, but my diet is far from being truly keto or low carb. I eat too much fruit and root veggies. I know the answer lies somewhere in the low carb/intermittent fasting world – I just have to figure out how to make it work for me. Hope things are going better for you!

        1. So far so good, especially since I am using it to deal with chronic health issues

    2. I have had this happen. I also had a extreme gout attack,where I was given a shot and put on alpunerol and was eating tums like candy.. So with that said, I started alpunerol and then read side effects and quickly got off it after 2 weeks. The way I cured this was drinking more water and adding a little salt to my diet. (Pink Himalayan). I also added pyssilym powder to my am cup of coffee (decaff) which includes a tiny squirt of stevia and a tablespoon of coconut oil. I’ve found that going keto is an experiment at first,but you need to make it a way of life. Once you find what works it’s really awesome. I’ve experienced all the ups and downs. But In the end it’s really worth it if you get yourself adapted to keto as a lifestyle not a diet. On another note if you need cheat meals and what have you ,Well then it’s just a diet and diets always fail.

      1. Thanks Bob – I agree that I need to find a way to make this work for me. I’ve been thru all diets, and I just know this is the right way to go. I remember back when I did the first version of the South Beach Diet – lost like 14 lbs. in 3 weeks, but as soon as I reintroduced a piece of fruit every day, I stopped losing weight. I had read that for some people, too much coconut oil can cause acid reflux. When I was doing this last spring, I did add a lot of coconut oil or butter to my coffee every day. Perhaps this was a big part of it. So, I’m curious – what does adding psyllium powder to your coffee help with? Keeping the gout at bay?

        1. I had to give up most fruit because of digestive problems and ibs-d. For some reason, once I entered menopause, my body seemed to react negatively to too much fruit. It’s weird how different we can all react to certain things. I can’t eat cream cheese or blue cheese any more, either or I break out really badly :/

    3. That sucks Sandy! If you love the keto lifestyle, you can find a way that works for you. It’s possible that nightshades or eggs or nuts or citrus or dairy aren’t working for you, and if you don’t eat one of those things you’ll be totally fine. I would also recommend adding a high-quality probiotic (unless you have an autoimmune condition) – Mark’s probiotic is awesome actually 🙂 Good luck with it.

      1. Thanks Charlotte – I’ve had one of those tests done before for food sensitivity, and there were a few things that I am supposed to avoid. You are right that dairy could be one thing that doesn’t work for me, because I eat a lot of cheese and drink lactose free whole milk. I’ve been taking a probiotic for a few years now, but thanks for the tip about Mark’s brand. Thanks for taking the time to respond. I’ve been thinking maybe my next step should be trying a Whole30 and see what happens.

        1. Sandy I’ve been paleo for 6 years and when I did my first Whole 30 4 years ago it still changed my life. I recommend it to everybody! I’ve done a Whole30 at least once/year since then – 5 total. It’s so good and there’s so much positive support out there and that it really makes the difference for a lot of people.

  15. What are your thoughts about acacia fiber? I have chronic constipation and that has helped me in the past…

  16. I suspect some of the keto flu may also be withdrawal symptoms from other food addictions like wheat, milk, caffeine, etc. For constipation, if you have been eating the same kind of thing for a long time, your gut will get optimized for that diet, so it can take a while to adapt to a new diet. For those who have gut damage, it can take longer. Magnesium will usually speed up the program fast though! ;-P

  17. You mentioned An ideal TC/HDL ratio is 3.5:1 or lower. Do you know how long it typically takes to go from a bad TC/HDL ratio to a lower one and is that an indication of reversal of insulin resistance?

  18. When first going paleo, i guess i went into ketosis. I felt like i had the flu for about 4 days,–achy body, no energy. I kept trying to find something online but couldn’t. I did find some stuff about the grain flu, so figured i was withdrawing from grains. After experiencing that, i was more determined to stay the course. Get thet stuff out of my body for good. I felt great after 4 days and have so many benefits now 18 months later So glad i found this way!! Thanks so much for all the info and encouragement. It has been life saving! I couldn’t have done it without you! Blessings!

  19. I’ve found (n=1) that a pinch of Himalayan salt and/or a teaspoon of coconut oil now and then really helps when I start feeling foggy or my energy level drops right when I’m shifting back into ketosis.

    This past year I’ve been training almost exclusively with the Olympic lifts (and auxiliary compound lifts), which puts me squarely in the “quick bursts of speed with rest in between, and feats of explosive strength” regime. I find training low carb / keto works great, but I really have to up the carbs right after or I start feeling really foggy after my post-workout meal (presumably from gluconeogenesis?). It doesn’t take much, just a cup of berries and a few slices of raw sweet potato, but without them I feel very foggy and my post-workout recovery is very slow.

    1. Seth, do you also use iodized salt for your thyroid at all? I was told by a chemist that Himalayan salt is virtually no different than ordinary rock salt (the pink color comes from iron oxide which he said I could scrape off an old car and add to rock salt and have the same thing) and the trace minerals (including uranium!) are so miniscule as to render them not worth the extra money at all. I now use both regular white sea salt and iodized table salt for my thyroid. Frankly, I was stunned by what he told us and have done as much reading as I can, but some sites still push pink, grey and other sea and rock salts for unproven health benefits…It gets confusing, but he was so convincing I decided to just use regular salts and save my money. I’d love to know what others know about this whole question, too.

  20. If you’re apoE4 and cholesterol and LDL go up on keto does that matter if you’re ratios are still excellent TG / HDL of 0.5 and total / HDL of 3!? Also, why the insomnia on keto despite lots of magnesium ( citrate or food grade) and plenty of Himalayan pink salt and avocados etc? I have tried keto on and off for last 2years ( been primal and low carb for 3) and can never get a good night’s sleep- wake up with a craving for the scrapings from a roast!

  21. I don’t understand why I’m still hungry all the time while trying to go keto. I didn’t feel this way when I was just doing primal, but also I had stopped losing weight with primal and now I lost 2 pounds in 3 weeks. My clothes do fit very differently however.

    I was eating primal for 14 weeks before starting keto. I’m not sleeping well nor feeling rested when I awake. I feel overheated sometimes. I haven’t tested, but I get the feeling that I’m not in ketosis because I still experience hunger. I’m avoiding all sweeteners, grains, legumes, polyunsaturated fats, and starchy vegetables.

    I’m logging what I eat to make sure I’m under 50 carbs. I do get confused with tracking carbs, though, because Mark says to count gross carbs, not net, but then he says not to count non-starchy vegetables. It makes it hard to track on my tracker. I guess I need to stop tracking the vegetables on the tracker, but I want to make sure I’m eating enough of them. I wish I knew if I’m doing something wrong. I feel like I’m being careful and intentional.

    1. I had the same problem for months. I found that making sure I had 12 hours between dinner and breakfast, no snacks!, and nutrient and calorie dense meals 3x a day works well. I had unbelievable hunger all day until implementing these small changes. Makes your body more sensitive to leptin. Also, make sure to drink lots of water! The pang you feel 3 hours after eating could be your body wanting some fluid. Check out Healthful Pursuit. Leanne gives some great tips for personalizing keto to fit your individual body. You are doing a good job being intuitive about how you feel and could use that same approach for eating and figuring out what your body is asking you for.

      1. I agree! I am cooking my way through Leanne’s new book The Keto Diet and listen to her podcast every Sunday. I love how she talks a lot about women’s health issues. Healthful Pursuit and MDA are my favorite sources of knowledge and recipes.

    2. Keto really requires that you drop carbs to no more than 20 grams total per day. The key to fighting off hunger is eating higher fat in order to feel satiated. You also really do need to get in sufficient sodium too, to ward off the keto flu. Good luck! It does work if you get get going with it.

  22. I have been experiencing pretty severe leg cramps while sleeping. I take a magnesium supplement. I’ve been drinking Natural Calm at night. I eat avacodos
    almost daily. I drink plenty of water. The cramps are all through the night very disturbing. I’ve been on the keto diet for 6 weeks. Any suggestions what else I could do?

    1. I was surprised cramps weren’t listed in the article. Mark has mentioned having them while going keto.

  23. Avocado supplies 1000mg of potassium, not magnesium(it’s around 50-70mg). This article is gonna sell the shite out of avocados unless you fix it.

    1. Paul Insco, thanks for the catch. Typo on my part. Larger avocados can provide 1000 mg potassium and up to 70 mg magnesium as you say. No one wants a run on avocados. Grok on!

  24. I’ve enjoyed reading you for years. I suggest that adequate salt/potassium/magnesium but especially salt can solve fatigue and poop issues. My personal experience was years cycling between Wahls level 2 and level 3 (keto) for years, but could never sustain keto for too long due to fatigue. I hadn’t salted my food for 10+ years, tried salting, 1-2 g but felt no better. Finally jumped off the cliff and aimed for 5 g (recommended by Phinney, Kresser, and research) and the bone crushing fatigue and poop resolved in a week.

  25. Interesting that in this article Mark says women with adrenal fatigue do not do well on keto when elsewhere he recommends keto for same women. There are some great comments below. I wish Mark would respond. I wonder how many fans he loses to other blogs that do respond. I have several times asked about ketosis and diabetes 2. How to safely do it watching blood sugar numbers and urinary ketones

    1. Mark’s views on keto are interesting but ultimately he is still a Primal sort of guy. He obviously has that dialed in. For keto you would be better of looking at other sites that get into things very deep. For the ladies Tuitnutrition is a good read.

    2. Pip Wood, thanks for your comment. Hormonal questions around keto are nuanced as is doing keto while diabetic. I have a post for each topic coming in the next six weeks or so. I’ll be doing more around keto for women as well with women guest experts who can supplement my research with more personal experience and insight. Best, Mark

  26. I have been primal for 5 years after finding Mark’s work online. Felt great but this past summer wanted to dial in a little fat loss. Keto worked for that but caused insomnia, hair loss, an autoimmune flare, and joint aches. I had boundless energy and intense concentration, but overall it caused detriments to my health. I do not think keto works for everyone and people should approach it with caution.

    1. I agree Laura – myself, and 2 other women I know over 40 had issues with keto (and one of them was a FNP). Someone else commented elsewhere that “common sense is a big part of this, so those who “cant” do it are probably not able to read labels”. I find that comment rude and condescending. Just because it works for a lot of people, doesn’t mean it works for everyone. We are all different in what our bodies can/cannot tolerate. I hope you find something that works well for YOU Laura.

  27. I have tried Keto three times. Each time I’ve had terrible nausea and even vomiting for the first week or so. After that it gets better.

    Seems to be a pattern: my whole life, whenever I ate deep-fried or very greasy food I’d be up vomiting in the middle of the night. No history of gallbladder issues or digestive troubles.

    After doing some research, including on MDA, I now suspect my gallbladder is just lazy and it takes about a week for bile production to ramp up enough to break down all the extra fat. Anyone ever have this problem?

    1. I haven’t had any vomiting, but when I start going into ketosis, I have allot of nausea, extreme fatigue and I am very cold which is off because being menapausal I am always hot. This last for a good 3 to 4 days. It sucks. I sleep allot!

  28. Like a lot of things, you have to give the body time to adapt – this is why I laugh when I hear people saying “I’m going on a month detox diet” – and they do some sort of restrictive crazy diet, only to go off the deep end in a junk food frenzy “catch up” when they finish it – you have to have a consistent approach to anything.

  29. You can go keto to reduce your fat,the muscles will deflate, then you carb load for the photo shoot to get the “shrink wrap” look.

  30. Hey Mark, I’m wondering if you can speak to the body odor side effect that many of us have been talking about: experiencing increased body odor in ketosis, especially underarm (people talk about breath but that’s not my primary concern atm). Is there an imbalance that you know of that causes this? On fbook groups people point to detoxing from previously poisonous foods, but I’ve been strict paleo/primal for 6 years, so not sure that’s what it is for me.

    1. Perhaps it is the deodorant you use? I cannot use the typical deodorant, it doesn’t work AT ALL on me, or just a few days. I now use the kind that is just a paste and no antiperspirant added to it. Schmits I think?

      1. I don’t use deodorant. Never needed it (at least not since I was a teenager). I don’t want to add it to my routine if I don’t absolutely have to. I’ll probably have to make it myself since ingredients are such a big concern (auto-iummune) and I’m so poor. I’d MUCH rather figure out the root cause.

        1. I use avocado oil now for face/body lotion including underarms, and other areas that typically produce odor. Remember that our skin – our ‘third kidney’ hosts its own microbiome and that body odors associated with sweat are waste products of bacteria that live on and in our skin. I figured that feeding my ‘good topical bugs’ is better that introducing chemicals to cover ‘bad-bug-’ poop odor, I have noticed that my clothes have less underarm and other=area odor, even no odor, after a long day. I’ve heard that others use coconut oil with success, but for me the avocado oil is more moisturizing. You may give either one of those oils a try!

  31. What do you mean, “1,000mg” of magnesium in an avocado???

  32. General comment: ketodietapp just published an excellent article on the Importance of Potassium in Low-Carb Diets and where to get it []; check it out!

    Also, and as Mark pointed out, being very low carb, can effect the amount of fiber one consumes. To those unfamiliar, I recommend incorporating Shirataki noodles into their meals. Not only they provide ample fiber (4.5 grams of fiber per 100 gram), they also have negligible amount of sugar and carbs and perfect for those with autoimmune issues, who can’t utilized other sources. My favorite way of eating them is via ramen soup. Recipe stays the same while the source of protein changes.

    By the way, has anyone watched “Life below zero”? I’ve recently come across the show and really enjoy seeing how people living at the remote corners of Alaska live of the land. Since they sustain themselves by eating game meat and lots of fats (“without fats we will be in trouble physically..”), they must in ketosis most of the time and definitely during the long winter months.

    1. Thanks for the heads up re:Shirataki noodles and Life Below Zero–sounds good.

  33. I must be some kind of freak because as far as “irregularity” goes, my experience has been the opposite of everyone else, my husband included. I’ve been more regular since on keto than I’ve been in years! One of the many “perks” being keto for me anyway.

  34. Wow, reading some of these comments is quite entertaining. I’ve been living Keto for 60+ days, dropped 25 pounds and feel so much better. My knees are no longer burdened or sore and I sleep better. Common sense is a big part of this, so those who “cant” do it are probably not able to read labels….Thx for the crucifer corpses LOL

    1. A whole 60+ days eh? THAT is entertaining. I think keto is good to cycle off and on. It seems many people are enthused the first couple of months of keto, but after a while they encounter a host of problems. Glad it’s working for you, if you get some of the common symptoms down the road you can up your intake of veggies and berries for a while and see what happens. I think Mark suggested cycling keto in previous articles.

  35. So far, so good. I am loving keto. I really think that it is perfectly geared toward overweight and older women. Go hang out on some of the women only keto web sites and get ready to be *ucking amazed at the results that are happening (the more overweight the better the results seem to be). I’ve dabbled in paleo and primal for years, but always fell off. I did a 95/5 primal for September and have been keto since October 1st. Besides losing weight without any hunger or ANY cravings and vast improvements in many health issues, I feel so amazing and joyful. Just a general feeling of well being. NOT my default mood, LOL. The best part is that dabbling here and there and spending the first month primal, I did not have keto flu at all. I do take calms magnesium, sauerkraut brine, cod liver oil, so that helps. Anyway, this is a big thumbs up for keto!

    1. Can you name some of these women focused keto websites? I would very much like to visit those..

  36. It’s easy to look at the side effects and say the diet is a bad idea. But honestly, any dramatic change to diet or lifestyle is going to have some negative impacts.

    The trick seems to be to figure out what is actually causing those outcomes and your details here are a fantastic place to start.

  37. Hi I hope this is not a dumb question but Will chewing sugar free gum cause an insulin spike? I’m currently going keto (loving the new book by the way!!) I work in close contact with the public and am always aware of breath freshness so I chew a lot of gum and just worried that it may be defeating my good intentions

  38. Wow that list alone is enough to suggest that going keto isn’t exactly ideal. In my opinion, keto is a starvation response and can be used as a good therapy for those who have certain health issues but probably shouldn’t be used as the latest fad diet. If keto gives side effects then instead of trying to counter those side effects, just ditch keto. In my opinion stirring up interest keto just to sell a new book is just plain irresponsible. Mark, looking at your website now, it just looks like a big money grab. It’s easy to see how people who aren’t paleo/primal think that this is just a money making scam.

  39. Do you have a good resource that explains why saturated fat and monounsaturated fats do not cause cholesterol. That it is the inflammation from sugar and carbs that cause our bodies to create cholesterol.

  40. Keto is very easy. Get your macros right by using a calculator. Make the “bulk” of your foods the most nurtrient dense + lowest carb veggies you can find and learn how to cook them in the best fats, spices, vinegars, and extracts so they taste amazing. Make these the center pieces of every meal period. Eat the most nutrient dense sources of animal protein/offal and treat it like a condiment to the whole meal, not the center piece. Same with salads although they’re admittedly not my favorite I like hot food Drink alot of water. Consider eliminating all sweets and booze.
    Lastly, if you find it “boring” or “hard” to stay on track, find yourself easily distracted and tempted by SAD foods especially, and struggling to get decent sleep, they are all linked to fight or flight and you are likely still sugar addicted or insulin resistant. You need to train out sweets and just go back to step 1 above.
    Eat keto aligned nutrient dense macros. Give it time. Don’t try to fast beyond your own comfort levels or work too hard until you drop the main thrust of excess body fat if you’re overweight. You know when cuz you’ll feel it.
    The ingredients required to induce nutritional ketosis are easy to execute but are a little specific and picky. Failure to prep beforehand with time to process the whole foods in advance of a busy life is also a natural derailer. In the age of information, ignorance is a choice. Keto is an elite diet. Anyone who can do the work to discipline for primal eating can and should relish the opportunity to take the next step. We’re not elitists like vegans but we are a group of people on the leading edge of modern nutrition and health. Make the switch.

  41. After reading through lots of these comments, I have to say that I really think a ketogenic diet is something to approach gradually. If you do that, there will be none of these side effects.
    If you are keeping to a Primal lifestyle and diet, it is not a big change. But still, gradual is better!
    When I am trying to lose a bit of weight, I tend to go toward a ketogenic diet. But I am never worried about whether or not I am producing ketones, etc. If I am feeling good, and losing weight slowly, I am happy. I just stick to above-ground vegetables (some raw, some cooked), meats, and plain dairy during my days. I do tend to end the day with one piece of fresh fruit, or a fig or two, or a prune or two, or a date or two, in order to relax and sleep better. It works like a charm!

  42. Hi there Mark, so far have lost 15 pounds since switching to a more primal diet. So far, so good. I talk to other people who are into bodybuilding and lifting and some of them are on Keto, some of them are not. A lot of them say things like what you are talking about, with regard to high cholesterol, and it is nice to have some real science to present to them instead of the usual outdated and uninformed health advice. Thanks for the information!

  43. Oh! Hey! I have another side effect to talk about. Every so often, it’s like the air pressure suddenly drops. My ears get that airplane feeling kids chew gum for and my skin feels like it’s moving outward. It happened on the way to the gym 90 minutes ago, accompanied by the first time by a feeling of wooziness. It passed quickly, and I had a normal workout. I’m in the third day of a three-day fast, so I’m pretty sure I’m ketotic, and this happened (without the wooziness) a couple of times during my 6-week keto reset period back in July and August. It could be a sudden drop in blood pressure. Or a sudden systemic shift off of sugar, although that should have happened two days ago.

  44. Can you have a cup of bone broth in the mornings you are fasting, I usually do 16 8 fast most days

  45. I have been doing Keto for almost a month. I’m eating lots of veg but over the last week, my bowl movements are like every 3 days and normal just infrequent. I’m not eating as much so I wonder if it’s ok? Had anyone else had thei experience?

  46. Reminds me, I was thinking that those who are epigenetically predisposed to a diet containing a lot of seafood might benefit from an increased dietary intake of other nutrients found in seafoods that I don’t remember being mentioned in Mark’s DNA test post like iodine and selenium, maybe salt.

  47. I’ve been keto for almost a month now, using the urine strips plus the cheap breathalyzer to measure (at .5 back on the breathalyzer). I have a big A salad every day with spinach, chard, and kale mixed greens, a whole avocado, and primal dressing. Many times plus a cheese I grate and then either some meat, or a light scoop protein shake with heavy cream. In general I feel awesome, but the last couple of days I seem to have some pain the the bladder or something, feeling like I need to pee even when I don’t, etc. Is eating raw spinach, kale, and chard every single day too much oxalates? Anything else I should be considering? I like to keep things simple and eat the same everyday, at least for lunch. Thoughts on if there is some sort of issue I may be creating for myself?

  48. What a great article, covering different symptoms. There always seems to be new ones everyday, but i guess everyone is a bit different. I got a symptom of feeling off balance for a second or two. Like an air pressure drop come to think of it after reading one of the comments.

    My guess maybe oxygenated blood circulation, but I’m not 100% sure.

  49. Hi,
    First of all I’d like to thank You for this site. So much useful info and great recipes ?
    I would also like to ask You for Your help in solving my problem.
    I’ve been on keto diet for three weeks now. In the first week or so I lost 4,4 lbs (196 to 191,8 lbs, height 65 in)then the weight just stopped. Now, in the fourth week of my diet, the weight is higher-193, 5 lbs.In the first two weeks I cut my calorie intake to 1700 kcal per day-maybe that’s too much? Too big of a shock for my body? Then I raised the intake to 2000 kcal and I really don’t know if I did right. Does my body gain weight because I cut the calories too drastically or because I eat too much fat and should reduce it? My macros are: fat 75% 161 g,protein 25% 98 g and carbs 5% 24 g. I’m insulin resistant, my morning blood sugar is 95-111 mg/dl whereas after meals it’s 80-105 mg/dl. I feel drowsy,no burst of energy whatsoever. I take supplements and drink a lot of water.
    I would be very grateful if You helped me with this situation as I’ve run out of ideas and I’m really starting to loose faith in ever going back to my old weight.
    Thank You