I’ve been reading and hearing about the supposed benefits of intermittent fasting for some time now. Several bloggers I follow have recommended intermittent fasting, including Mark Sisson, Richard Nikoley, and Dr. Mike Eades. Richard (of the Free the Animal blog) in particular seems to have good success with IF. 

I never tried it, however, for the simple reason that going 24 hours or more without eating sounded rather awful. Whenever I tried very-low calorie diets, I was usually halfway to miserable by bedtime on the first day … cranky, mentally foggy, and waaaay hungry. I remember trying to get by on Slim-Fast for breakfast and lunch, only to find my hands shaking by mid-afternoon. I would be counting the minutes until dinner, when I could eat a real meal.

Of course, I tried those low-calorie diets back when I was living primarily on carbohydrates and had conditioned myself to be a sugar-burner. Now that I’m on a low-carb diet and have conditioned my body to depend primarily on fat for fuel, I often skip breakfast anyway just because I’m not hungry yet. So when I recently listened to a podcast about intermittent fasting, it occurred to me that I could probably try a 24-hour fast now without feeling miserable.

It so happened that I slept late on Wednesday, and by the time I finished dealing with emails, DVD orders, blog comments, and a couple of phone calls with clients, it was already 2:00 p.m. My last meal had been some sliced turkey at midnight, so if I could just go without eating for another 10 hours, I’d have a 24-hour fast under my belt.

I haven’t read up on intermittent fasting nearly as much as Mike Eades or Richard Nikoley, but from what I understand, the benefits are largely hormonal. Insulin levels come down, while both glucagon and human growth hormone go up. Some body-builders claim intermittent fasting not only makes them leaner, but stronger, thanks to the human growth hormone.

So, what the heck, I decided to push on through until midnight without eating. (I did, however, start the day with my usual big cup of coffee. You don’t want to be anywhere near me if I don’t get my morning coffee.)

The biggest surprise was how easy it was. I felt a few “Feed me, Seymour!” grumbles around dinnertime, but they passed. No mental fog, no shakes, no sudden urges to beat my children. I can only assume my body was doing a good job of mobilizing fatty acids and ketones for fuel.

I considered going to bed without eating, but decided 24 hours was good enough for my first fast. I ate some turkey and a handful of almonds at midnight.  (My wife, a dedicated bargain shopper, bought turkeys on sale before Christmas and froze them. I believe we’ll be having a roasted turkey once per month until the Fourth of July.)

My first fast was so painless, I decided to try a 36-hour fast next. On Saturday night, I indulged in some red wine, cheese, and two big handfuls of mixed nuts while watching “Band of Brothers” on DVD. As is often the case when I eat a late-night meal, I wasn’t hungry at all on Sunday morning. I didn’t have plans for the day other than reading and watching the football playoffs, so it seemed like a good choice for an all-day fast.

Once again, I was surprised at how painless it was. Curious as to why I didn’t have the shakes or feel light-headed, I checked my blood glucose around 6:00 PM and was surprised see it was around 95. It’s usually in the 85-90 range when I wake up in the morning. Apparently my body was adjusting with no trouble.

From an evolutionary standpoint, it all makes sense, of course. Paleolithic hunters almost certainly had to go without eating now and then, and if missing a few meals meant their hands were too shaky to toss a spear accurately, they’d miss quite a few more. We’re almost certainly well adapted to intermittent fasting, at least if what we eat day-to-day doesn’t mess up our ability to mobilize body fat for fuel when we need it. I couldn’t get by on Slim-Fast because I was an insulin-resistant sugar-burner consuming little cans of liquid sugar for meals.  Not enough sugar to get me through the day, and I couldn’t release fatty acids quickly enough to make up the difference.

I went to bed after midnight and slept like a rock. I was hungry when I woke up this morning, but the feeling went away after my first big cup of black coffee. I finally began to feel really and truly hungry around noon, which was the 36-hour mark. Fortunately, my wife had saved a ribeye steak from the dinner she served the girls last night. I ate about half the steak and a cup of her delicious chili, which is light on the beans and heavy on the ground beef.

I don’t know if I’ll ultimately continue intermittent fasting once per week, twice per week, or get bored with it altogether and stop. But since it was nowhere near as difficult as I anticipated, I’ll give it a shot for now. I’ll keep you posted on the results.

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70 Responses to “Intermittent Fasting”
  1. Soul says:

    I forgot about those sites. I’ll have to go through and read about others fasting experiences.

  2. Eric Lepine says:

    I too have to vouch for Mr. Berkhan’s approach here, gracieuseté de Richard Nikoley. It is by far the easiest method (if you don’t eat breakfast and eat your last meal of the day around 8pm, you get 16-hour fasting window every day) and for me, as for Martin, it has allowed my mind to think about food a bit less ;)

  3. Marc says:

    Being doing Martin Berkhan’s method for a while now and for me it is way the best method of cutting calories. I really don’t have too many problems getting my first meal of the day at around 7.00PM and if I were to do the accepted 6 meals a day of about 400 calories I think i’d be ready to kill after a couple of days. Fasted workouts are no problem either.

  4. Shaun says:

    Just four short months ago I was a slave to eating and training. My days went something like this: 6 am High-carb snack. 6.15 1 hour run with the dogs 7.30 High-carb breakfast 8am 2 hours on the kayak (with obligatory high-carb snack on any little island we came across). 11 am Another healthy high-carb snack before starting work where I’d constantly be snacking on those energy giving foods for athletes. In total, I’d say I was eating 8 times a day(yep, firm in my belief I was keeping my metabolism nice and high like all good athletes should, grazing like a muscular horse rather than stuffing myself like a fat bear).

    After work I’d spend 30 mins doing intense boxing circuits, burpees challenges etc. before walking the dogs for an hour or two. And I got fat! Yes, not just a little chubby but really fat. Then, thank God, I happened across Kurt Harris’ site, then Robb Wolf, then Tom Naughton and, now, 3 months into a Paleo way of living I trust my appetite and I fast naturally. I have my life back and I limit myself to one activity a day(and often I do nothing which was not an option with my former outlook.

    I realize I’m not saying anything new here, but by cutting out carbs and knocking 70 % of my previous exercise regime on the head I no longer have any of my arthritic pains, I’ve completely resculpted my body, I am never hungry, no tooth pain, I can enjoy lie-ins without the need to pound the streets to burn calories…

    The ridiculous thing is I used to be a personal trainer brought up in the good old ways of exercise more and follow the food pyramid. It wasn’t until my own metabolism got busted up that I had to reappraise everything I thought I knew. A sincere thanks, Tom, for the info you put up here (and in the movie). Now I just need a version in Spanish because I am having zero luck convincing people here that conventional wisdom is a crock.

    Isn’t it amazing how a change in diet can fix almost everything that’s wrong? Let’s hope Gary Taubes’ new book is a best seller and the publisher is inspired to release a Spanish version.

  5. I can’t do IF. For some reason, low carb pushes my blood sugar low and I cannot skip meals.

    Although I do forget to eat sometimes due to the appetite suppression of ketosis. But then it ends in hypoglycemia that leaves me feeling like homicide is an appropriate choice if it will result in a meal.

    M

    If you feel awful, I say listen to your body and don’t do it.

  6. Boosh says:

    I wonder how fasting would affect me. I have ADHD and maintaining a balance is critical to getting through the day. The brain consumes 20% of the body’s energy and ADHD brains [race car brains] might take even more energy.

    I’m curious to try fasting, but I’m always so damn hungry! I have been doing the paleo-thing for about a week and I’m loving the change in my body already. Maybe after I’m on it a bit longer I’ll try intermittent fasting.

    You may need more time to adjust before trying IF.

  7. Renee says:

    I went on a cruise with some friends this past summer, and for breakfast every morning I’d load my plate up with eggs, bacon or sausage, etc. from the buffet. My friends ate “heart-healthy-whole-grain” cereals, croissants, sugary yogurt, etc. If one of them ate a hard boiled egg, she wouldn’t eat the egg yolk. (More for me — I ate their egg yolks!)
    Anyway, after a breakfast like this, I would be raring to go, and come lunch time, would not be hungry at all. In fact, had I been on my own, I would have skipped lunches, and possibly dinner, too. But I was with five carb-fueled gals who not only were ravenous by noon (this, with breakfast at 9:30 or 10!!) but would want to interrupt our explorations to find snacks mid-morning and mid-afternoon.
    Eventually they noticed I wasn’t controlled by my hunger like they were.
    “I just don’t understand how you can’t be hungry yet,” they’d say.
    So I’d tell them I wasn’t hungry because I’d eaten a breakfast of fat and protein, which is much more satiating.
    “I ate a good breakfast, too!” they’d say. “I had whole grain cereal!”
    At which point I had to wonder what it would take to overcome their cognitive dissonance. If you are hungry two hours later on your diet, and I can eat once per day on mine…???? Anyone? Anyone?

    I was at an all-day meeting with a software client some time ago. They sent out for lunch, so I had a chicken salad. Their IT guy had a sandwich and chips. Around 3:30, he said, “We have to finish this up tomorrow. I’m brain-fried.” I think he was experiencing a blood-sugar drop. I could’ve kept going for hours.

  8. Al Fedoruk says:

    I have tried a couple of IFs as well. When I was a sugar burner, going a whole day without food was unthinkable. Being in a situation where food would not be available would make me nervous — better bring a ‘granola bar’.

    It is surprisingly easy when low-carbing. No shakes, no dizziness, no “Must. Eat. Now.” I commute to work by bicycle and I am even able to ride with no lack of energy (it is uphill both ways). There is a feeling of hunger, but it is easily ignorable hunger.

    I have started wondering about the usual diet advice to eat 5, 6 or more small meals per day. That is, never let yourself get hungry. If one is on a low-fat diet doing that (and even a low-carb diet) then it seems to be a recipe for keeping the body running on sugar and never touching the fat stores, because insulin levels will stay elevated all day long.

    I agree. Eating all day doesn’t make sense from an evolutionary perspective either.

  9. joe_mama says:

    If you’re lds(mormon), we do this once a month. The idea being, you fast for two meals, and the money you would have spent on the meals, you donate to charity. Definitely not as hard as it sounds, once the initial hunger passes, you’re usually fine the rest of the fast.

  10. Matthew says:

    Hi Tom, its good see more people become more aware of intermittent fasting. I’ve been doing intermittent fasting for about a year and half now. In combination with a diet lower in refined carbs (my fiancee makes amazing french toast and Chilean empanadas), I’ve maintained my weight while improving my metabolic panel (LDL down, HDL up, triglycerides way down).

    I also have to say I appreciate your edutainment efforts on fathead and it has helped inspire me to do my own experiment with a ketogenic diet combined with intermittent fasting:

    http://www.geekbeast.com/the-experiment/

    Thanks to intermittent fasting my entry into ketosis was a lot easier than what is described for most people. I’m already shocked with how stable and high my energy levels have become along with the clarity of thought when my brain is running on ketones.

    That looks like an interesting experiment. Keep us posted.

  11. Galina L. says:

    I was playing with the idea of IF myself for a while. It reminds me how it took me 3 years to start low-carbing. I thought it would be impossible. Started at least 2 times and stopped due to a migraine. You know how always hungry people feel. Now am happily in ketosis most of the time and should be ready for a next step. You provided your readers with a very good strategy – oversleep first. Second clue from people who responded – breakfast is not sacred. Do you mind to tell how do you have your coffee?

    I used to drink it with cream, but now I’ve switched to black coffee.

  12. Galina L. says:

    Do you think that we shouldn’t use a sugar substitute during IF? I think we shouldn’t but hope it is OK.

    I haven’t seen anything pro or con.

  13. js290 says:

    Boosh, take a look at the Evolutionary Psychiatry blog.

    Your brain on ketones.

    Western diet and ADHD.

  14. I have tried IF, too, but it was several months ago. I would be interested to know what podcast you were listening to that made you want to give it a shot.

    So, do you feel you benefited by the trial IF in any way? When I did it before, I lost weight.

    It was a podcast with Brad Pilon, but I can’t find that particular one. Should’ve bookmarked it. It feels like I’ve lost a little weight, but it’s too soon to tell.

  15. Helen says:

    I recently listened to an older podcast on Jimmy Moore with a Dr. Thomas Seyfried. He researches the effect of ketogenic diets on various diseased individuals including brain cancer victims. He categorically stated that if everyone fasted for 7 to 10 days once a year, no one would ever get cancer. Anyone know anything about this….

  16. Julia says:

    Just a thought for anyone having trouble maintaining energy while IFing. I do cheat with coconut oil. I have read something about coconut oil sending the body into ketosis. It does seem to give me the lift I need to maintain. OK, I guess I”m not technically fasting, but it seems to work well for me.
    And, it does get MUCH easier over time, took about a month of 24 hour fasts about twice a week for me to really adjust, and now I actually look forward to it.

    I find it’s getting easier too. Earlier this week (after skipping breakfast, as I usually do) I was running errands that took longer than expected and ended up going 22 hours without eating, with only some coffee and cream in between. I was only aware of being hungry for about the las hour.

  17. Another interesting point about the Minnesota Experiment is that the two subjects who started with the most muscle mass had the least amount of metabolic complications.

  18. Lucky Joestar says:

    I’ve been doing intermittent fasting for several months now. My fasts are only 16 hours, but I do them every day, and they’re working, taking me down from the 84 kilograms I weighed a year ago to around 73 kilograms at present. My goal is to get down to 65 or so by December.

    My mom, a true believer in the “eat breakfast to lose weight” mantra, claimed I’d “balloon up” on the day I announced I’d stop eating breakfast. I haven’t ballooned up one bit. Seriously, how do you get fat from eating less?

    You don’t.

  19. Aqua Tard says:

    I have been taking 5 cocanut oil capsules for breakfast and 5 capsules for lunch 5 days a week for the last 5 months. I have also been taking a table spoon of fiber powder in water each time I take the cocanut capsules. I eat regularly at night. I don’t get hungery during the day and I have not had the brain fog or energy loss I had with just fasting. I have been lossing a steady 5 pounds a month for the last 5 months. Krogers has had the cocanut oil capsules on sale, buy one get one free so it only costs me $13 for breakfast and lunch for 24 days ($0.55 a day), which is a bonus

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