Marks Daily Apple
Serving up health and fitness insights (daily, of course) with a side of irreverence.
25 Apr

Why Fast? Part Seven – Q&A

By now, you should be caught up on all the benefits that fasting offers. By now, you’re likely either intrigued by the practice, strongly considering taking it up, or basking in the smug satisfaction that your longtime breakfast-skipping ways weren’t destroying your metabolism after all. But although I tried to cover just about everything I could in the last six posts of this fasting series (links at the bottom of this article), I apparently didn’t hit every angle, because I received a barrage of questions from readers via email and comments looking for clarifications, answers, and explanations. I can’t quite answer them all, but I did manage to put together a fairly representative selection of the most common and relevant ones, and today I’ll provide answers.

I would like to IF but I have osteopenia and am concerned about losing bone mass. I have been gluten/dairy free for three years and paleolithic for about 3 months. Would IF be good for me?

Your hesitance is understandable, as caloric restriction has long been associated with bone loss, likely due to the reduction in circulating IGF-1 (insulin like growth factor 1) levels. Since intermittent fasting does not appear to have the same effect on IGF-1 levels, however, I’d imagine it’s pretty safe for bone health. Just make sure you’re eating enough calories when you do eat (the IF rodents in the study did not reduce calories overall) and lift some heavy stuff now and then, and I think you’ll be good to go.

There was a study that found in utero IF had a negative effect on fetal skeletal development, but you’re not typing this question from the womb, right? If so, amazing!

Won’t IF induce the body to break down muscle to get amino acids for de novo gluconeogenesis?

Let me hammer this point home: Once you become a fat-burning and keto-adapted beast, most of your energy demands will be met by stored fat and ketones, so you won’t need to eat protein to spare muscle. If you are fat-adapted and keto-adapted, fasting (at least IF) is protein sparing. If you DO need to get some glucose for a hard workout, some will come from glycerol (from triglyceride) and some from de novo gluconeogenesis. But you won’t need much from muscle tissue because your glucose requirements have dropped, you are better at burning fats and ketones, and, presumably you are NOT doing a 2-hour blood-letting in the gym.

As I often say, this is NOT the case when you are a sugar-burner. Then you probably DO need some protein to stoke the gluconeogenesis process, and I’d suggest eating a protein-rich meal (see Meat) before you embark on your fast so your body will have plenty of dietary amino acids on which to draw for gluconeogenesis. Of course, this doesn’t apply to all you fat-burning readers out there. To you I say, don’t worry about muscle loss during IF.

Workout intensity? Should I just be a slug during the fast, normal activity (long, slow walks or bike rides), intense workouts? Intense workouts usually make me hungry shortly after.

Long walks are great while fasting. My favorite pastime is an early morning hike on an empty stomach. I typically fast for a couple hours after my resistance training to maximize growth hormone, but then again, these days I’m generally doing bodyweight exercises (sometimes supplemented with a weight vest). Most sources say to end your fast with a workout and eat afterwards. If intense workouts make you hungry, save them for the end of the fast. That way you can derive the benefits of a long fast, the benefits of a fasted workout, and the benefits of a massive feast after it all. Win win win.

Above all, I would stay as active as possible during the fast. Sitting around like a slug will only make you dwell on food, and the lack thereof in your body. Don’t do that unless you want to obsess over what you’re not eating. Walk, ride a bike, get some work done, do housework, read something. Just keep mind and body active.

I am on a regimented meal/medication plan. I am adopting the Primal lifestyle, but I need to make room to allow for the tasting of these products. Sure, the menu items I can handle, as I just really need to take a couple bites, and that is it. The problem comes from having to taste for quality of the other items, like sauces that an employee makes, for consistency sake. In each, I might only have to taste a teaspoon or two at most to correct for seasoning, but when you have 10 items to test, that adds up.

How would you manage something like this? Would you make the working hours like a fast or something, to account for the tasting?

How does a chef fit the Primal Protocol?

Sounds like a great job to me! Personally, I wouldn’t worry a whole lot about fasting, especially as you start a new job and acclimate to a new schedule. Plus you have a family, which can add even more stress (love you, kids). Intermittent fasting might heap another stressor onto your busy schedule, so keep that in mind.

If you’re dead set on it, though, there are two ways you can incorporate fasting into your schedule, as I see it. First option: don’t sweat the tastings. You’re only doing a teaspoon at a time (and you could probably cut that to half a teaspoon, am I right?), and since fasting is not controlled by an on/off switch, you won’t necessarily be “breaking” the fast. Just consider your work day your fasting period. You’ll be on your feet throughout the fast, so you’ll be staying active and your mind will be engaged with things other than food. Er, scratch that: you’ll be engaged with food, but not necessarily eating it.

Another option is to fast on your off days. Assuming you get a day or two off, just do a full-on legitimate fast for one of them. It doesn’t have to be a full 24 hours or anything, but try to make it at least 16 or 18 hours without eating. Good luck!

Are you suggesting that it really is OK to skip breakfast?

Yes, I am. While epidemiology suggests that breakfast skippers are fatter and less healthy, that’s a correlation, not necessarily causation. It could just as easily be explained by the fact that people are more likely to skip breakfast because they’re overweight and want to lose weight. Or maybe because skipping breakfast is widely regarded as an unhealthy activity (like eating red meat), those who are already healthy are more likely to eat breakfast. See how it works? To date, there has never been research conclusively showing that skipping breakfast causes the metabolism to “slow down” or the skipper to gain more weight. In fact, the bulk of the evidence suggests that meal frequency and timing have no effect on weight gain or health (and it might even be the opposite, as my fasting series suggests).

What frequency do you recommend the average guy on Primal/paleo fast?

It depends entirely on the duration of your fasts. If you’re doing a Leangains-esque slightly compressed eating window, daily fasts are in order and even well-tolerated. If you’re doing longer fasts that stretch toward 24 hours and beyond, once a week is all you “need.” Two would be fine, as well, but any more often might make it difficult to obtain enough calories to prevent the negative effects we often see with chronic calorie restriction – muscle wasting, bone mineral density reduction, libido lowering, general malaise.

Can I drink coffee or tea during a fast? How about adding cream or coconut oil to it – will that take me out of the fasted state?

Coffee is actually beneficial for fat-burning, especially during a fast. One study found that an infusion of epinephrine – a hormone which coffee increases – during “starvation” enhanced its lipolytic and thermogenic effects. In other words, fat-burning and metabolism up-regulated in response to epinephrine (more so than usual). Epinephrine also lowers appetite, which can be extremely helpful for people trying to stave off hunger during a fast. Tea, and anything non-caloric, is also fine.

Adding a pure fat source won’t “take you out” of the fasted state, and it may take the edge off the hunger, but it will reduce the body fat you burn by a bit.

One should eat protein and carbs 30-60m post workout to build the muscles. Am I wrong?

If your sole intent is to get stronger, build muscle, and pack on weight – all fine, commendable goals – then, yes, you should eat some protein and carbs within an hour of working out. Of course, this is totally compatible with fasting. Just end your fast with a workout, and feast right after.

I play competitive sports 3d/week. Should one make sure to eat on the days one plays sports? Or is it more important to eat the day after?

Personally, I would eat on game days. It might be fun to try out a few fasted games, just to see how you perform, but the likely optimal way to integrate fasting into competition is to save the fasting days for your training days. By doing this, you’ll be “training low, playing high,” which should result in some beneficial adaptations after training and improved performance in the game (when you’re “high,” or fully replete with nutrients and calories).

Should fasting be considered when you try to GAIN weight?

Usually, no. But there are a couple special cases where fasting might help someone gain mass.

I’ve mentioned Leangains a number of times in the past several posts, and I’ll do it again. It’s right there in the name: “lean” and “gains.” Plenty of people have success gaining lean mass on the 16/8 Leangains IF plan. It’s slower gaining, but it minimizes and sometimes even eradicates fat gain. Of course, you also have to be sure to lift heavy weights and overfeed on training days (most find the two are a natural pairing, though).

I’ve also heard from people who used intermittent fasting to increase their appetite to the point where eating enough calories to gain weight was possible. The constant snacking was keeping them perpetually full, whereas a good solid 18-20 hour fast really ramped up their hunger and allowed them to eat an actual meal.

Can I take vitamins or supplements during a fast?

Sure, but absorption might be hampered without a meal to go along with it. Vitamin and mineral absorption is generally better in the presence of food, particularly fat. For instance, vitamin K2 is absorbed seven times greater when taken with a meal than without (PDF). I personally skip the supplements when I fast.

I’m actually posting this in a fasted state. It’s been about 20 hours since my last meal. Should I keep fasting till I hit the 48 hour mark? I’m not really hungry, but I’ve been doing the one meal a day thing for some time. Thoughts?

Sure, give it a shot. I always say that pushing the limits is healthy from time to time. Plus, this will give you a good baseline. If you know you can fast for, say, 36 hours without doing too much damage or incurring too much stress, you’ll know your limits for the future. People have fasted for far longer and lived to tell the tale, and you seem to be reasonably experienced. Good luck.

Should pregnant or breastfeeding mothers do it?

Probably not. Whatever you do, listen to your hunger signaling. Don’t force yourself to adhere to an arbitrary fasting regimen just because it’s shown to confer all sorts of benefits in other, non-pregnant populations. While I wasn’t able to find any studies on breastfeeding and fasting, there are several on maternal fasting:

There have been studies on calorie restriction and lactation, and it looks like mild calorie restriction (coupled with exercise) has little impact on breastfeeding. If you’re going to do this, make sure your milk quality and quantity aren’t negatively affected. Keep the fasts short (12-ish hours) and infrequent, just to be safe. And, of course, consult your doctor prior to doing it.

Should I fast if I’m trying to get pregnant?

Generally, no. Fasting is a stressor, and if you’re already stressed out over something and cortisol is high (say, because you’re trying to get pregnant and finding it difficult), throwing a fast on top of that will likely compound the problem and make it harder to get pregnant. Cortisol is a potent inhibitor of fertility.

However, if you find that fasting improves your health, reduces your weight, enhances your metabolism, fixes your metabolic syndrome, which can all have negative effects on fertility, it will likely have a net benefit. If you intend on fasting, opt for the “WHEN” method rather than a regimented one, and keep your fasts pretty short. Fertility requires “plenty.” An extended fast does not exactly send that message to your body. A 12 hour fast every once in awhile should probably be the limit, and only if it’s improving other subjective and objective markers of health.

On the other hand, men who are trying to impregnate someone may find it helpful to fast.

Should kids do it?

Kids shouldn’t be put on a fasting regimen or anything like that, but they might forget to eat now and again, and that’s totally fine. As a kid, I often spent my summer days in a fasted state from early morning through early evening, simply because I was out running around, playing capture the flag, skipping rocks, and generally getting into trouble. It didn’t always occur to me to eat. I think I turned out okay.

Should seniors do it?

Seniors should absolutely try it. Although we’re talking elderly humans here, elderly rats derive a lot of beneficial neurological effects from intermittent fasting. I see no reason why older folks can’t also enjoy the neurological, life-extending, and health-promoting benefits of fasting, too. It might increase healthspan, stave off age-related cognitive decline, and improve quality of life.

Under what circumstances would you recommend that someone not fast?

High stress. Overtraining. Chronic lack of sleep. SAD dieting. And then there’s my previous take on the subject.

I’m thinking about giving IF a try and am wondering if you have any thoughts on how to track its effectiveness. Would you recommend a logbook? What should I be recording and looking for?

I think for many people looking to track the effectiveness of a given fasting protocol, a logbook can be extremely helpful. Think of it like a training log for your workouts. You can track:

  • Objective measures, like weight, body fat percentage, waistline, blood sugar, dress size, hours slept, plus markers of physical performance, like weight lifted, reps completed, distance run/walked/cycled/rowed. These are easy to track, as they come with numerical figures built-in.
  • Subjective measures, like mood, energy levels upon waking, energy levels halfway through the fast, energy levels during workouts, perceived performance during cognitive tasks. These are trickier to track, so you may want to assign numerical figures to them in order to quantify what is essentially a subjective measurement. Something as simple as rating your mood 1-10, with 1 being “very bad” and 10 being “very good,” should suffice.

And if you’re fasting for a specific health effect, say to boost the effectiveness of chemotherapy, you’ll definitely want to track those specific health markers.

Ultimately, what I hope this series has done is inspire you to self-experiment with fasting. I always maintain that fasting is not essential to Primal living, but it certainly seems to mesh well with it. Whatever you do or don’t do, I want to stress something: don’t stress out over this stuff. If you’re going to give it a shot, do so and do so intelligently – by tracking your progress, maybe even doing so formally – but don’t drive yourself crazy obsessing over the minutiae. Whatever you do, good luck!

Here’s the entire series for easy reference:

Why Fast? Part One – Weight Loss

Why Fast? Part Two – Cancer

Why Fast? Part Three – Longevity

Why Fast? Part Four – Brain Health

Why Fast? Part Five – Exercise

Why Fast? Part Six – Choosing a Method

Why Fast? Part Seven – Q&A

Dear Mark: Women and Intermittent Fasting

You want comments? We got comments:

Imagine you’re George Clooney. Take a moment to admire your grooming and wit. Okay, now imagine someone walks up to you and asks, “What’s your name?” You say, “I’m George Clooney.” Or maybe you say, “I’m the Clooninator!” You don’t say “I’m George of George Clooney Sells Movies Blog” and you certainly don’t say, “I’m Clooney Weight Loss Plan”. So while spam is technically meat, it ain’t anywhere near Primal. Please nickname yourself something your friends would call you.

  1. Fasting is more than a tool. It’s my power tool.

    Grokitmus Primal wrote on April 25th, 2012
  2. Since I am in my late 60s, I fast to stimulate autophagy. Studies have shown any of these things will stop autophagy dead in its tracks:

    Raised insulin levels

    Because coffee and tea contain antioxidants, you don’t want to drink anything other than water during your fast.

    Supplements are out during a autophagy fast. Those pills may contain antioxidants plus we do not know all of the things that may stop autophagy.

    The safe rule for autophagy fasts is nothing goes into your mouth except water.

    Jake wrote on April 25th, 2012
    • I agree with you, but not completely. Most people don’t know it, but coffee is very insulinogenic. However, this doesn’t mean people should fear it, or stop drinking it during a fast, but it is insulinogenic for the reasons your named, and it can put a damper on autophagy in some cases.

      Another interesting way to fast is to omit protein from the diet for an extended period of time. A nutrient deprivation of any number of amino acids will immensely stimulate the process of autophagy. This concept has roots in an ancestral diet.

      Hunting was sometimes unsuccessful for days, maybe weeks, and foraging was really the only way to eat. The main exception is that they weren’t able to, or trying to, piece together a semi-decent amino acid profile from beans and nuts the way vegans do, so they were missing a lot of essential amino acids in the their diet.

      Enter profound autophagy.

      Of course the concept of temporarily eating only vegetables and fruits sounds a little sacrilegious on this website.

      So, for example, you can be deficient in some amino acids, the body will recognize the nutrient deprivation by kick starting autophagy, and it won’t care if you drink a cup of coffee or not.

      I do like your rule of nothing goes in but water, although I don’t think you will negate all the benefits of autophagy, with coffee or supplements, however protein will have a bigger impact on negating benefits.

      I write about autophagy, youth, and growth hormone extensively on my website, as well as how fasting impacts more interesting things such as telomerase, and telomere length.

      Matthew Caton wrote on April 25th, 2012
      • Matthew… I sure would like to know your website address, as it sounds to me that you really know whereof you speak!

        martha wrote on April 25th, 2012
        • Just scroll over Matthew’s name – you’ll notice it is a link to his site.

          Dave wrote on April 30th, 2012
      • This study came out a few years after your reply. All I can say about it is please do drink lots of coffee caffeinated or decaf for greater autophagy.

        Bob wrote on June 3rd, 2015
  3. What a great, comprehensive series. Really appreciate this. Gros merci!

    Stéphane wrote on April 25th, 2012
  4. Im in the UK and don’t have a SAD diet, recently trying to go primal from a fairly healthy diet.

    Whats the longest period of time for someone trying to lose weight fast for? I normally do a 36 hour fast. The longest I have done is 58-60 hours (2 full days+night) but at the end of it I was shaking inside and out really badly, although it stopped when I ate something – is this a common side effect for fasting?

    molly wrote on April 25th, 2012
    • It sounds like you did an n=1 experiment and found that 36 hours is the right length for you.

      Harry Mossman wrote on April 25th, 2012
    • Sounds like you’re carb addicted & still running on glucose, when your body is in lypolysis/ketosis mode you don’t get hypoglycemia shakes & your blood sugar levels & energy state are very stable because your body has adapted to using your body fat for energy & is making ketones & so is making energy, including the little bit of glucose you need to prevent the shakes.

      cancerclasses wrote on April 25th, 2012
    • Are you already lean and skinny? I have read that happening to people who fast with nothing in reserve. Had you any dependencies on medication like caffeine? Maybe a withdrawl. I your metabolism still sugar and carb versus fat burning? Then there was no energy for the brain and muscles.

      Is it common side effect? No! A fast will leave you feeling light, a good lean body that is tight in it’s musculature, and with mental clarity, even spiritually sensitive.

      So I would say you might try a supervised fast. A qualified healthcare professional will check you for electrolyte depletion and other signs to stop the fast, or give you proper veggie juices and minerals to keep you in the fast.

      RobG wrote on April 26th, 2012
  5. Totally agree with the stress. With my semester coming to an end and finals around the corner my stress is off the charts and I was fasting beforehand but this is the second time this week I broke into a mad binge (grains included). I can’t keep it up right now but I’m definitely getting back on it when I’m done with all this

    Steffo wrote on April 25th, 2012
    • reading this as i am downing the last soda of my finals week… I’m in your boat! I am not looking forward to the fatigue/fog I’m about to endure while I detox from massive amounts of carbs over the last week. Time to get back to it! Thankfully I haven’t ‘outgrown’ my jeans.

      Stephanie wrote on April 26th, 2012
  6. “Under what circumstances would you recommend that someone not fast?

    High stress. Overtraining. Chronic lack of sleep.”

    I think I disagree with these! Fasting helped me with my lack of sleep and I think I get less stressed when fasting (lessens the dependance on food to relieve stress)!

    And as for overtraining, fasting might help break the mental cycle of compulsive eating and exercise?

    Any thoughts?

    ChaiKe wrote on April 25th, 2012
    • I sleep better when I fast during the day, eat at night. I also find that fasting is a has a great calming for me, but like Mark said, your body should be fat-adapted before fasting, otherwise you probably won’t find fasting as calming as I do.

      I see where Mark is coming from with high-stress. A diet with good fats is calming. The original use of the cannabinoid receptor.

      You definitely don’t want to fast if you are overtraining, but then again, you definitely don’t want to be overtraining. Best cure for overtraining, is stop training.

      Matthew Caton wrote on April 25th, 2012
      • How long before you are “fat-adapted”? I have been eating Primal for about 2-1/2 weeks, went through a stage of feeling half stoned after the first week for a few days. Am I ready?

        Turtle wrote on April 26th, 2012
        • LOL, if you no longer feel half stoned and are still eating Primal then you’re probably ready. Give it a shot, start with a short one from dinner one day to lunch the next and see how you do.

          K wrote on April 26th, 2012
  7. I wish a fast could be completed as quickly as the name suggests. I’ve had a lot of experience with caloric restriction but have never fasted a full day. The closest I’ve probably come is spending half a night hiking through fields and rural backcountry in a fatigued and semi-fasted state and then not catching up on calories until the next evening or the time I slept away a whole weekend to recover from stressors, only waking and getting up to go the bathroom and quench my thirst with milk.

    Animanarchy wrote on April 25th, 2012
    • After having the same results as you had, I decided to wait awhile to fast again. I’m hazarding a guess here, but it may be that your body was not ready to fast, though your mind was.

      I also have found that doing a completely food-free fast takes some practice (skipping meals here and there, pushing mealtimes off by an hour, then two) but is MUCH easier to complete than caloric restriction. I have no idea why except that perhaps I was confusing my body by being around plenty of food but only providing it a little, instead of taking the “None for now” mindset.

      Anyway, just thought I’d share that it isn’t hopeless! I also don’t think it’s supposed to be miserable, so I’d encourage you to keep plugging away at different techniques until you find one that doesn’t make you suffer :)

      Meg wrote on April 25th, 2012
      • Again, abstaining from food completely is easier than intermittent EATING because when you avoid eating long enough for your body to go into lypolysis/ketosis it starts making energy from your stored body fat. Eating ANYTHING gives your body a supply of fuel to digest & so it doesn’t need to go into fat burning mode, and insulin from carbs & high blood glucose specifically shuts off lypolysis, the breaking down stored body fat, & also stops ketosis, converting that broken down body fat into ketone bodies, which the body also doesn’t need to do because you just put something in your stomach that your body can use for fuel.

        Think of it like this: when a car runs out of gas its out of fuel for energy, it stops dead. The body, however, is like a car that runs out of gas and then, as a back up system, starts digesting the spare tire & rubber upholstry to convert that into gas so it can keep going. But then when you stop at the next gas station & put fuel in the tank the car stops breaking its self down & resumes running off the fuel you just put in the tank BECAUSE ITS EASIER and requires less of its own energy than converting the parts into fuel. The upside is that as the car digests it’s rubber & plastic parts it gets lighter, loses weight & actually gets better mileage & can go farther on the same gallon of gas because it weighs less.

        Make sense? I’d buy a car that could do that in a heartbeat, you NEVER have to worry about running out of gas & getting stuck out in the middle if nowhere or in a bad neighborhood in the middle of the night.

        You are also correct that intermittent eating teases & stimulates the bodys leptin & ghrellin – hunger/satiety responses and makes you want to keep eating. So yeah, all or nothing works better than intermittent snacking when you’re trying to do a fast, if you’re not intentionally trying to burn stored body fat then it doesn’t matter much, eat if & when you’re hungry as long as you understand that everything you eat puts fuel in your tank that your body will use for energy instead of using your body fat.

        cancerclasses wrote on April 25th, 2012
        • Right on. Except I think the car wouldn’t strip anything vital off of itself. Instead it would clean all dirt, grease, mud, and the sticky mess in your cup-holder from the drink you spilled a little bit of about a month ago, and it would use that as fuel, and then you would have a clean car.

          Matthew Caton wrote on April 25th, 2012
        • Why not? The body strips the vital fat stores off its self when it needs to or is forced to that it has taken time & energy to build, after all that’s why & what it’s there for.

          In the context of fasting the point is that skipping breakfast, lunch or dinner, or all three for a day or three days or five or 10 or two weeks isn’t gonna kill you, digest your muscles or any other horrible thing, provided you at a normal level of health.

          You’ll be fine, that’s how the body is designed to work, otherwise we’d have all gone extinct long ago. But I do think it’s a sad commentary on life in an affluent society that the majority of people can’t & haven’t ever gone more a few hours without eating & without totally freaking out & having a major psychological breakdown on everybody around them.

          A minimum 3 day water only fast should be on EVERYBODY’S bucket list, solely for the **mostly psychological** confidence that comes with knowing you can do it if you ever have to and for the confidence in having achieved mastery over your mind & body as opposed to being led around your entire life by your stomach.

          cancerclasses wrote on April 25th, 2012
    • I think that fasting works best when you are keto adapted, as Mark says. While showing ketones in your urine may only take a few days, that is not an indication that you are keto (fat) adapted. Becoming fully keto adapted can take several weeks; maybe you could try becoming keto adapted and try IF again with less issue,

      Barb wrote on April 25th, 2012
    • The exercise and fasting combo was what concerned me the most when I began IF. I now fast for a 24 hour period from dinner Sunday to dinner Monday. On Monday morning when I wake up, I go through a short and deliberately paced yoga routine, usually sun salutations mixed with a combination of warrior poses. I have found that this combo of IF and yoga works great for me, allowing me to continue exercising through my IF.

      Read more:

      Cliff wrote on April 25th, 2012
  8. I have, somewhat grudgingly, started doing IF. Generally I don’t eat until I am hungry, which could be noon. If I wake up hungry, I eat immediately then maybe have a light salad at lunch.

    I realize now how leaden I feel after eating (even eating primal food) and how light and flexible I feel when fasting. It is quite dramatic.

    Harry Mossman wrote on April 25th, 2012
  9. I fast sometimes to give my digestive system a break from the continuous breakdown of food.

    Paul Alexander wrote on April 25th, 2012
  10. FWIW, as a breastfeeding mom, I fasted around 40 hours and didn’t notice any problems at all. Moms will, though, want to make sure they drink extra water to make up for the extra fluids that they would normally get in food-form.

    Also, the things I measure when I fast are the things that concern me most about the process. Energy levels, emotional impact, weight, and hunger levels were what I typically focus on, because that is what I’m hoping fasting will impact, so that’s all I bother with.

    Meg wrote on April 25th, 2012
    • I tandem nurse and I have been fine eating from 2:30 – 7:30pm. So basically a 19 hour fast. I do this for about five days and on the weekend I will do lunch

      Diane wrote on April 25th, 2012
    • When you say “fasted around 40 hours”: how often? I’m breastfeeding and doing IF too (I skip lunch every day); a bit worried by what Mark said on this…

      Lemurette wrote on April 26th, 2012
  11. Is 2 week old kombucha appropriate during an IF? Please say yes.

    Joshua wrote on April 25th, 2012
    • I drink it during my fast. Homemade stuff. I figure it gives the probiotics room to work!

      Diane wrote on April 25th, 2012
  12. The exercise and fasting combo was what concerned me the most when I began IF. I now fast for a 24 hour period from dinner Sunday to dinner Monday. On Monday morning when I wake up, I go through a short and deliberately paced yoga routine, usually sun salutations mixed with a combination of warrior poses. I have found that this combo of IF and yoga works great for me, allowing me to continue exercising through my IF.

    Cliff wrote on April 25th, 2012
  13. Hello all, I completed my first IF this week. I fasted for 24 hours. It went really well. I wasn’t nearly as hungry as I thought I would be. I’ve been primal for a while (down 75lbs, I have another 25 to go). I finished my fast at 7pm on Monday night. I had a mild workout around 6pm. And I went to bed around 9:30. I woke up around 2am and my body felt like it was buzzing. I couldn’t sleep for nearly an hour. Is this normal?

    Shamonn wrote on April 25th, 2012
    • Could be. If I break my fast with a workout and a meal, I am often glowing a few hours after the meal, which is a nice feeling. Especially if the workout was intensive and if the meal included ample carbs. Fortunately, I never had it so bad that I could not sleep or would wake up.

      Victor Venema wrote on April 25th, 2012
    • Read this article on sleep. It will help your understanding of that pattern. I sleep like this fairly often. Sometimes I’ll get up for about an hour, maybe two, and read etc. Before I started doing this I went overseas to a few places that aren’t littered with TV/computer screens… crazy right? I found it odd that people would be up in the middle of the night reading, or talking.

      However, it is a very natural way to sleep. I think Mark love-linked this article a while back, so thank you Mark.

      Matthew Caton wrote on April 25th, 2012
      • Thank you guys for the insight!

        Shamonn wrote on April 26th, 2012
    • The autophagy of fasting induces biochemical changes which make you more anabolic (muscle-gaining) the next time you work out after the fast. Your short-term, subjective experience will be that your metabolism is revved up.

      Fasting, then working out, then eating, then going to bed right away.. probably not a good plan.

      Jeffrey of Troy wrote on April 25th, 2012
  14. Thanks a lot! I find it very helpful.

    Vlad wrote on April 25th, 2012
  15. Thanks for this series on IF. I have been intetested in giving it a try to assist with weight loss. I loved hearing about all the other benefits I can gain from IFing. Great info!

    primal gigi wrote on April 25th, 2012
  16. Does anyone else fast by skipping dinner instead of breakfast?

    oxide wrote on April 25th, 2012
    • I do botdinner then breakfast the next day! Works great!

      Rochelle Hamel wrote on April 25th, 2012
    • I did last night and woke up feeling more like myself than I have in a while.

      Animanarchy wrote on April 26th, 2012
      • I should try this soon. I always do breakfast because I really hate breakfast anyway but I bet fasting from lunch on would make me feel great the next day. I wonder how I would sleep though.

        K wrote on April 26th, 2012
  17. Great series!

    I was previously doing long fasts once or twice a week but have since adopted skipping breakfast instead and I find it to be much more manageable. If I’m really hungry at breakfast I might eat something but normally it can wait. My fasts normally last from 6pm to 11am the next day and 3 days out of the week, I do an intense workout (LHT or Sprint followed by easy cycling) for an hour total before breaking the fast. My performance has been fine and I feel better if I don’t eat breakfast and just have a black coffee instead (french press style of course). I’m in the Dietetics program and they all think I’m nuts for adhering to a Primal lifestyle but FYI we did a cholesterol screening lab yesterday and my total cholesterol was 131. BAM!

    Emily Mekeel wrote on April 25th, 2012
    • It doesn’t matter. They’ll just say you have “good genetics” and go back to stuffing themselves with whole grain Lean Cuisine pasta. :roll:

      oxide wrote on April 25th, 2012
      • Haha, agreed. But, I’m glad you’re challenging them, Emily.

        You should drink raw eggs in front of them, haha, they might have you committed.

        Matthew Caton wrote on April 25th, 2012
        • Before they took my blood, my friend (who knows I’m Primal) asked what I had for lunch. I responded: homemade beef jerky, hard boiled eggs, walnuts, and really good parmesan cheese.
          The reaction from everyone was silence.

          Emily Mekeel wrote on April 25th, 2012
      • I got that response right out of the gate! I acknowledged that genetics is a potential factor. I still walked away feeling validated 😉

        Emily Mekeel wrote on April 25th, 2012
  18. I am a fitness instructor! an injury in January forced me to cut back from a probably “Chronic Cardio” schedule. I work with seniors and am trying to incorporate Primal exercises into my routines. Any tips? Thanks! R. Hamel

    Rochelle Hamel wrote on April 25th, 2012
  19. I love IF, it has really changed my life for the better, i have lost 1 stone in 1 month by just having one meal a day at 8pm, i drink water / tea and coffee during the day, i found the first 24 hours the hardest, but i could not believe how my appetite decreased and for the first time i was not hungry and i felt in control of my eating, it has also made me much calmer, and i am not depressed anymore, my eyesight has improved, my skin looks younger, my brain is much sharper, i’ve lots of energy, my sleep is deeper, my type 2 diabetes is gone, wow i just can’t believe how amazing IF is for you, i plan on following this eating plan for the rest of my life, thanks Mark for spreading the word! You saved my life!

    Irene wrote on April 25th, 2012
  20. I love intermittent fasting! I typically do 18-hour daily fasts, sometimes I’ll break early around 16 hours if I am hungry. I also take days off as I believe it’s natural to have varied intake and intermittent fasting is just one component of that. It’s great, especially for its convenience and not feeling deprived of anything. I still eat large volumes but waiting creates a deficit for me. I’d recommend it to anyone who can keep up with it.

    j3nn wrote on April 25th, 2012
  21. I’ve been on the GAPS diet for 2 weeks and have designated Sundays for my 24 hour fasting day. Yet, both times that I’ve fasted on the GAPS diet, I’ve gotten sudden intense vertigo and a heart rate or 50-52/60. Should I continue to fast one day a week?

    kalyn wrote on April 25th, 2012
    • @kalyn: I would consider it unsafe for a patient to continue after that kind of reaction, and I’d be especially concerned if it represents a dramatic change from your normal blood pressure. I’d advise a full medical workup, including a workup by a cardiologist, both on a normal and fast day. They may invite you to wear a holter monitor for a week or so. It’s important to understand that BP drops much *further* while you’re asleep. Good luck.

      Art wrote on March 4th, 2013
  22. Ever since I was a kid, I’ve hated to eat in the mornings. It felt like the worst kind of chore. I share your experiences of being out an about as kid and, having tons of energy, and never feeling hungry of the need to eat.

    Now that I skip breakfast, and often lunch, I can just get up and start going, without worrying about eating. It’s great.

    Matthew Caton wrote on April 25th, 2012
  23. I like to use fasting to get me back to 80/20 when I have a few rough days in a row. I start by skipping breakfast, than a few days later skip breakfast and push lunch back an hour or two. It makes Primal easier for me when it gets tough.

    Molly wrote on April 25th, 2012
  24. How do you know when you are fat-adapted?

    Marisol wrote on April 25th, 2012
    • Try an IF and see how you feel. If you feel like roadkill after 10 hours, you are probably not fat adapted. If you feel like going another 10 hours after the first 10, congratulations – you are adapted.

      Joshua wrote on April 26th, 2012
    • Glad to see that question, as I was going to ask!

      I’ve only been primal 2 weeks, though pretty strictly I think.
      I had a few days at the end of the first week where I felt tired and cold, and wasn’t sure if that was the low carb flu, or just night shift-jet lag.
      That passed, but I still quite often feel a bit sleepy mid afternoon, I’ve not noticed any significant body changes, or extra energy yet. And although I wouldn’t say I have specific cravings I still find myself fantasising about cakes and bagels from time to time. (I can’t believe I’ll ever fantasise that way about a steak- however good!)

      I figured I’ll give it another week or two before I try a deliberate fast, although I have made a conscious decision to eat breakfast at work when i get hungry, rather than at 5.30 am before i leave home, meaning my overnight ‘fast’ is now more like 12-14 hours instead of 9.

      If anyone else has any tips on how to tell when you’re fat adapted I’d love to know.

      jade wrote on February 9th, 2013
  25. I train 3 mornings a week from 7-8am. The workouts are military based strength and conditioning sessions. Always random. I prefer to train fasted then continue the fast until I get home at about 7pm – then I feast.

    Does anyone else do this? Is this a good idea, bad idea? Anyone care to share their experiences?

    Damien wrote on April 25th, 2012
  26. I have been doing leangains style and really like it. The transition has been fairly smooth. I have experienced some nausea. I have searched for others with similar experience and have not found much. Any ideas?

    Mariah wrote on April 25th, 2012
    • I have been experiencing the same thing. Been primal/paleo ‘ish’ (toy with dairy and higher fruit contents) since 2008 and every time I get ‘serious’ about primal and try to eliminate all but veg, fat, and meat, I get very nauseated, lethargic, and low blood pressure.
      I chalk it up to some sort of electrolyte imbalance (I’m sensitive!) so I try to sea-salt a lot, but every once in a while I feel heavy like I’m going to puke…this happened to me yesterday, so I drank 1/2 cup coconut water and BAM I was recharged.
      Can’t figure out if I can do LC or not. I’ve been doing it for 16 days not and finally caved to the coconut water (and an orange! the horror!) and I felt amazing yesterday into today. Hm.

      Camila wrote on April 26th, 2012
      • It’s possible to go TOO low carb – this sounds like an n=1 experiment that tells you your body needs a slightly higher range of “low carb.”

        Me, I feel best (and lose weight best) when I’m eating just meat and fat. I throw in vegetables when they’re too hard to avoid (at the bottom of my chopped salad!) and fruit whenever I see a blackberry (a few times a month).

        But primal/paleo isn’t cookie-cutter – the trick is to find the level that works for you and helps you meet your goals while still feeling great!

        Merryish wrote on April 26th, 2012
        • In my own n=1 experiments over the past year, I’ve realized that all I really want to eat in the winter is meat and fat. I can’t recall the last salad I ate–I think it was in October. Other than garlic, shallots, chiles, and the occasional can of crushed tomatoes it was almost a veg-free winter, and I felt great (even as my old programming kept screaming that I needed to eat my vegetables–season be damned!–and despite having no desire for them).

          Now spring has sprung, and I’m eating lots of asparagus, Brussels sprouts, and dandelion greens (from my yard). They’re delicious, and they’re exactly what I want to eat right now. I don’t want berries, but I know that when berry season rolls around I will. And by the time summer kicks off I’ll be back to living on enormous chopped salads once again.

          So yeah, everyone is going to have their own way of way of doing this that is right for them. When confronted with the question, “Am I doing this right?” my answer is always going to be “Is it working for you?”

          Melissa. wrote on April 29th, 2012
  27. Great series of articles. I use Martin’s Lean Gains method

    -=HoFF=- wrote on April 25th, 2012
  28. continued from above…(button slip, posting from phone, sorry!)

    As I was saying….I use the Lean Gains method and really enjoy it. I work out late so my fasting is done during the day, light meal at dinner time, workout a few hours later, eat again afterwards. Best part is the flexibility. No stress about food anymore. Used to graze all day, and was easily 10-20lbs heavier on average.

    Typically do 16-18 hour daily fasts, but have stretched it out a few times to 20+. I’m going to give a longer fast a try now.

    Thanks again for the great articles; I’ll be passing these along to others!

    -=HoFF=- wrote on April 25th, 2012
  29. Hi Mariah,

    It happens occasionally to me too; I usually sip some water and it passes quickly. I’ve found this occurred more when first switching to this approach though, and not very frequently as you adapt to it. Another trick is to find something else to keep your mind on, rather than thinking about your stomach/food. Good luck!

    -=HoFF=- wrote on April 25th, 2012
  30. Very conficting info on this subject. I’m currenty reading a book titled “The Smarter Science of Slim” by Jonathan Bailor. He makes a pretty convincing argument based on real scientific studies over many years that fasting or calorie restriction actually causes you to get fatter in the long run as you’re fighting against your body’s weight set-point and fasting actually makes your body want to store more fat. The science seems to suggest the *quality* of your food is what determines your fat levels and a weight set-point which is tightly regulated by the body. Any attempt to force it down with calorie restriction almost always leads to failure in the long run and more weight being gained. I’m sure many of you here have experienced this. Jon Gabriel also makes the same argument in his book ‘The Gabriel Method’. Perhaps IF is best suited for people who are already at their ideal weight and have no hormone imbalance issues? Anyone here read these books?

    George wrote on April 26th, 2012
    • I loved the Gabriel Method. I think ultimately he advocates IF. His quote at the end says ‘eat like thin people’ because they will skip a meal and not even notice it, and will only eat when hungry which might be quite a while if no physical activity has occurred.

      And he is also advocates ‘quality addition’ instead of subtractions. Instead of removing pastry from your diet, you add superfoods. They displace the other items and the body quickly associates it with real food that is nutrient rich bringing satiation.

      So I agree with everything you said. Fasting before the body has recovered health, he would say, is just triggering your body for famine response of ‘we need to get fat’. And ‘when your body wants to be fat, there is no way to win that battle’. Awesome book!

      RobG wrote on April 26th, 2012
  31. I have been primal/low carb for about 4 years now. I have lost 60 lbs. When I was down about 40 lbs though I went through a really rough period in my life and fasted for 40 days straight for religious reasons. Fasting had always scared me before. I lost the last 20 lbs that I wanted to lose and everything in my life got MUCH better! Since then fasting has not scared me and I do IF during the week (Mon-Fri). I only eat from 4 PM til 8 PM, then I feast! I eat good things though. On the weekends I am a bit more lax and go out to eat sometimes, but I am able to maintain my 60 lb weight loss like this with no problem. I can eat the amount that I want when I do eat and that was a big thing for me. I am a 5’2″ woman so it is much different I am sure for some of the 6 foot tall men on here.

    Shannon wrote on April 26th, 2012
  32. Started Paleo in October. At first I had serious Glucose withdrawal; it lasted for about a week – 10 days. I felt as stupid as stupid can get. fortunately I knew that it would end so I kept it up and lost 12 lbs or so. NO EXERCISE. I sit all day for my job.

    Then after reading the first in this excellent series, I fasted for 8 days. I never lost the hunger growls, but I was able to keep working and my concentration was thru the roof. You can not imagine all the extra time you have in the day when you take food off the schedule. Since then, I have been one meal day only – all Paleo.

    Just got my blood work done and my body seems to love it. I have also lost 35 more lbs. well on my way of 100lbs in a year. I have no loss of concentration at work, and I don’t get cranky or short. I also don’t eat as much as I use too at dinner.

    Try it you’ll like it.

    Once Upon a Time wrote on April 26th, 2012
  33. Animanarchy wrote on April 26th, 2012
  34. I really enjoy fasting, I will do a 30 hour fast generally speaking at least once a week. I find that my thinking is actually clearer as the day progresses and I have a lot more energy. It’s actually hard to eat the next day. I also do the Master Cleanse once or twice a year for 10 days. While not really primal because of the maple syrup, I really like the effect it has on my body. I think of it as a reboot to just let everything rest for a while. It’s also very empowering.

    Venture11 wrote on April 26th, 2012
  35. I haven’t read through all the comments but I’ve read the series and have learned quite a bit. I never needed to be sold on the concept of fasting…I more or less have just needed to find the right time to start…which brings me to my question…when do I start?


    Female, athlete up through college (125lbs to 130lbs), now at least 150lbs with orthopedic conditions do to my own laziness.

    Will be 30 this year and I’ve yet to accomplish all my fitness goals.

    Total Type A, paralysis by analysis type that cannot for the life of me finish something. I’d like my 30th birthday gift to myself be to accomplish my fitness goals.

    Former personal trainer/fitness guru gone south. NSCA-PT, CrossFit & KB to certified couch potato and stress ball.

    Ex bodybuilder-esque gym goer gone crossfitter.

    So it seems to me all we had to do was look at the life of a dog to see the beauty in the science: eat 2x daily, sleep, play, rinse and repeat! My dog is lean, fit with a beautiful coat…why can’t I have that!!

    Life stressors have played a role in my self-imposed decline as had the budget. Which is one of the reasons why I’m attracted to fasting because I find “needing to eat” hugely stressful and costly. I just wish I never needed to eat really. My body isn’t in its best state ever and my anxiety and stress are wreaking havoc. I’m a total sugar-burner but find it hard to workout on an empty stomach…could be because I’ve always been a sugar burner and never have completed the dam task of accomplishing fat-burning and stuck with it! I am a huge paleo advocate … it’s just expensive to eat better food packed with protein, fruits and veggies. Period. Sigh…..

    So is it smart to start now???

    A part of me says “yes…do it finally.” It’s what you need to jump-start your transformation and get your mind back on the right path.

    The other part says “you will crash and burn” like the crazy carb-induced burner you’ve been. You’re stressed and ready to burst…is it really an awesome idea to go into deprivation mode.

    Then I go back to “no just do it for peeds sake because it’s not like you haven’t already done enough damage to yourself.”

    So again, paralysis by analysis…please help me stop the vicious cycle?!?!?!?!

    Patty wrote on April 26th, 2012
    • My advice? Get into fat-burning mode first. I cannot even begin to tell you how much easier fasting is when you’re in ketosis.

      And don’t feel you have to push yourself too hard in the beginning, either. I started by not eating anything between midnight and noon, then midnight and 2PM, then midnight and 4PM, etc., and I didn’t start doing longer fasts until I was comfortable with daily IF.

      As for the expense, yeah, good food does cost more up front. But speaking from my own experience, I’ve been eating significantly less as an IF’er, which more than offsets the higher cost of the food I do eat.

      I’m doing an 18/6 schedule most days, one all-I-can-eat day, and one full fast day a week. Within my eating “windows,” I eat only when I’m hungry and eat until I’m satisfied. But it doesn’t take much to do that–what I eat on any given evening is no more than dinner and a small snack used to be in my pre-IF days. If I was working out more I’d probably eat more, but I’d probably still eat less than I used to.

      In fact, if I had to identify my biggest problem as an IF’er, it’s that I still over-buy groceries. I keep realizing that I’ve got too much meat or fresh produce on hand that needs to be frozen or otherwise dealt with, because there’s just no way I can eat all of it before it goes bad. I spent a lot of years on a carb-heavy diet in which “stocking up” was economical, then switched to low-carb where I still ate a lot (two big meals a day, plus snacks and a small breakfast)–and those shopping habits are harder to break than I imagined.

      But I’ll say this–not having to think about the next meal all the time, and not having to deal with food prep, cooking and clean-up three or more times a day? It’s awesome. It’s so much easier to keep the kitchen clean, too! 😀

      Melissa. wrote on April 29th, 2012

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