My friend Tim Ferriss asked me to post an up to date version of my thoughts on intermittent fasting. I wrote a post about a year and a half ago on intermittent fasting that generated numerous comments and questions. Between then and now I’ve received many emails from readers who have gone on intermittent fasts, some with success, others with not so much. The early animal studies that looked so good prompted a number of researchers to look at intermittent fasting as a potential therapeutic tool for humans. I figured it was time for an update.
You can find my two part post on Tim’s blog.
Part I
Part II
I would be curious to hear from any and all who have given intermittent fasting a good solid try, so feel free to post your thoughts and/or results in the comments section.


  1. Really enjoy this blog.
    A couple of points:
    You seem to have approached IF as an excuse to eat carbs?
    You quote the Mattson study. Steve Mount has some interesting comments on this:
    “They found that people on a diet that involves a single meal each day show elevated fasting glucose levels and impaired glucose tolerance. This is in contrast to an earlier study (Johnson et al. 2007, Free Radical Biology and Medicine 42:665) that tested alternate day calorie restriction and found improved diabetes risk profiles (also see the Johnson upday downday diet, which is promoted by the same James B. Johnson). The authors suggest (in the Carlson et al. paper) (Mattson group) that the key difference is an overall reduction in energy intake.
    That may be true, but there are two other important differences between the Fast-5 approach and alternate day fasting (including my method of fasting three times each week from dinner one day until dinner the next day, which is less rigorous than a full bedtime-to-waking fast of 30+ hours). First, even a dinner-to-dinner fast is longer (roughly 23 hours, on average, as opposed to 19 or 20). If the benefits of fasting kick in after 12 hours or so, this difference could be more significant than one might otherwise think. Second, the consumption of all daily calories within a five hour window is very intense, and ad lib eating over 24 hours need not be. Between fasts I usually eat dinner, a late-night snack, breakfast, lunch and dinner. Less intense eating means less insulin secretion and less food in the stomach at the beginning of a fast, which would further increase the effective length of the fast.”
    I’ve been doing an IF about twice a week – fairly random – usually 2pm to 2pm. Quite happy and from what I am reading there are numerous health benefits:

    1. Hi Chris!
      When you have kept a dinner-to-dinner fast, so you have been about 23 hours without eating, how long time period you are able to eat after that before stopping again? And how long time you will usually fast after that eating period? Actually, would you like to tell me completely your style? What it is in a use?
      You say: “method of fasting three times each week from dinner one day until dinner the next day”.
      Would you like to write me what one week is in use then? : )
      Thanks very much

  2. For about six months I’ve been eating no more than two meals a day, most days (usually during the week) I only eat dinner. For about 95% of the meals I low-carb, although on weekends I’ll sometimes eat Mexican or Indian food. I haven’t lost weight, but I haven’t gained it either. I’m a desk jockey so I haven’t been hitting the gym and therefore haven’t seen if that adds into the whole IF thing. But I’ve gotten used to it, I don’t feel deprived at all. I was never a big breakfast eater anyway and it’s also gotten me out of the habit of mindless grazing. I’m not eating super-huge meals either. And the food tastes really good. :

  3. I’ve been following an IF + LC plan since August 2007, Dr. Mike. I feel like a different person. I’m losing weight, I’m no longer tied to scheduled ‘meal times’, I have all this energy, I sleep like the dead (I used to be a very light sleeper, waking every 2 hours) and perhaps the strangest changes; my vision has improved – dramatically.
    I eat for 8 hours every day, typically fasting from 8PM until Noon the next day. I workout 3-4 times a week, two of those workouts being with heavy weights. And I factor in some kind of ‘cheat’ every four or five days. Once a month I do a controlled refeed, a la CKD/ UD2.0. Normally my carbs are under 100g, not very LC, but it seems to work for me; I avoid anything refined and get most of these carbs from vegetables and fruits. I do splurge on 100% rye bread every now and then.
    I’ve created a plan for myself based on your initial posts on IF and PP (+PPLP), information I’ve read over at Lyle McDonald’s forum ( and Michael Pollan’s advice from An Eater’s Manifesto.
    The scale messes with my head, so I’m using measurements and clothing as a guide. I’ve lost 5″ off waist and hips and I’m down two dress sizes.
    I can’t say enough good things about IF.

  4. Mike,
    I gave it a try. First a 5 hour eating window, then just skipping breakfast. I did OK for about 2 weeks. Then I began to feel so bad before I ate that I thought I was going to die. There was no way to keep a normal weight on it. So, I cut it down to skipping breakfast and not eating until lunch. Still too much weight loss. Felt better, but not as good as if I had eaten breakfast.
    If I try fasting again, it’s just going to be once per week

  5. PS:
    My take is that these daily forms of fasting work only for people who are overweight to begin with, not for people of normal weight.

  6. I think IF is useful concept, but i think it should be more intermittent in nature, in that one should skip a meal here or there every so often. For instance, upon wakening go into the the “wild”, rather outside, and engage in some exercise. Then come back and have some good low carb fare. I think IF would indeed work for many if they consumed low-carb, high fat meals, as animals in the wild do, and indeed as many traditional peoples would have probably done. There was great programme on discovery channel a while back, here in Ireland, where two english guys lives with the Kombaii tribe some where in Papau New Guinea. The adult tribesmen, although short, had physiques that would make most fitness enthusiasts salivate. I suspect their body fat percentages were next to nothing, given their vascularity, abdominal visibility at all times, an in general their overall muscular definition. They subsisted mostly on big maggots, called grubs, fatty pig, and sago palm, a starch. While their diets consisted of alot of sago, i would assume that their diets were still relatively low-carb compared to most westerners. Anyways, they often went for days without eating, namely because of failed hunts or because the weather was so wet; they do not vacate their huts in the rain. Thus, it seems likely that they used ketones for fuel more than glucose. As a side note, what always strikes me about these “traditional peoples” programmes, is the lack of fruit. Alot paleo advocates recommend fruit in abundance and the avoidance of saturated fat, yet i never seem to see many fruit trees on these programmes. The only fruit that seems to feature prevalently are berries (low-carb of course). For instance, the other night, i watch a showed about nomadic reindeer herders in Siberia. Their diet consisted of animals, reindeer milk, which if i recall correctly contained 70% saturated fat, little vegetation and berries.

  7. Mike,
    I attempted intermittent fasting last year. I tried a one meal per day strategy where I consumed no calories for 20 hours and then did all of my eating in a four hour window. As a busy grad student, I was mostly interested in the time-saving benefits of not having to prepare breakfast and lunch.
    There were some positives: My blood pressure, which tends to be on the high side of normal (128/70) dropped like a rock within a couple of weeks to about 110/60. Also, some nagging aches and pains from my athletic endeavors went away, which makes me think that long spells without food were reducing inflammation. I usually eat few grains and no potatoes, but while I was doing IF I ate whatever I wanted.
    Ultimately though I couldn’t stay on the diet. I am an active guy and an ex-sprinter who still enjoy lifting weights and sprinting, and I simply couldn’t eat enough food during a four hour window to support my training. I was too tired to train, and I when I did train I didn’t have enough endurance to work hard. (this is with 3x weekly training). I lost around 8 lbs in four weeks and some of it was muscle mass. That was distressing to me.
    Another problem is that I felt like I was chained to my food supply during the four hours of my feeding window. I believed (apparently with some justification) that I had to spend that time constantly stuffing food down my throat in order to get enough calories and I just don’t enjoy feeling stuffed.
    I haven’t tried the 24/on 24/off that you attempted because, like you, I frequently have dinner engagements. Some day I may try the 20/4 protocol again, except I will simply reduce my calories and eat fruit and nuts during the day rather than eliminating calories completely. I’ve talked to people who have good success with a regimen like that.
    Hope this is a helpful data point.

  8. Dr. Eades,
    What about the Ramadan studies you mentioned earlier? Those were people and their blood markers improved.
    Also, I’m sure that the humans in the IF studies you site in this article were not on a low carb regime. You have mentioned before that low carb is similar to very low calorie in life extension effects. Perhaps IF on low carb is different than IF on a typical insulin producing diet?
    Thanks for all your great work. I look here everyday to see what is new.
    Philip Thackray

  9. I’m more interested in the longevity issues. Is spending a day or two a week ‘fasting’ going to reduce inflammation indicators, lengthen my lifespan, etc. without decreasing my muscle mass, making me unhealthy, or miserable in other ways? (What if combined with a low-carb diet? What if not?)
    Ever since Jr. High, I’ve been able to go a day or two here and there without eating. I don’t know that I could go every other day without eating, but just yesterday I didn’t eat until after 6 PM, after having had dinner around 7 the night before. I had a LARGE sirloin steak with a chopped garlic rub, and a couple small slices of cheese. the night before was a rib-eye with some coffee (Americano) with cream and half a pack of sweet-n-low. (I haven’t been able to afford the switch to grass-fed beef, yet, but I hope to in a month or so!) I also ate lunch and breakfast on Sunday (two double bacon cheeseburgers sans bun, and 4 eggs and 4 strips of bacon, respectively. I had the same breakfast again today, and probably won’t eat again until Dinner, after 7 or so (most likely my usual post-workout meal, Chik-Fil-A sandwiches, no buns, and nuggets).
    Since I’m doing a slow-cadence workout twice a week now (more like Adam Zickerman’s “Power of 10,” very similar to your, MD’s and Fred Hahn’s “Slow Burn”), I’m more concerned about getting enough protein and good fats (Saturated) to rebuild and strengthen muscle tissue while also losing fat. I have an ion-exchange whey protein drink (Iso-Pure, I haven’t tried your recommended Immuno-Pro yet) that I take from time to time, and I’m considering taking additional CLA, which I’ve read seems to promote fat burning while sparing muscle.
    My usual supplements right now are Vitamin D (I’ll probably stop or cut back once Spring is REALLY here. We’re expecting a couple inches of snow in St. Louis today, though!), A multi-vitamin without Iron, Krill Oil, Vitamin E (Carlson’s Elite, with tocopherols AND tocotrienols), Co Q10, Alpha Lipoic Acid, Chromium Piccolinate, and Potassium (Multiple times a day, when I think of it). I also take some magnesium citrate drink and fish oil in the evenings (Also, when i think about it). Although not really a ‘supplement,’ I’d like to start adding a glass or two of wine in the evenings, as well :-). That’ll come when I can afford the switch to grass-fed beef, too!
    For the month of March, I’m going to target fasting at least one day a week, having a ‘cheat’ day one day a week (St. Patricks Day is already scheduled!), trying to keep an average of 200 g of Protein a day (a little over 1 g per estimated lean body mass), less than 30 g of carbs a day (Except for ‘cheat’ days), and my usual supplements (Plus coffee, and green tea w/pomegranite, with a little saccharine and or cream in each). As of just now, I weigh 418 (fully clothed. I’m already 6 lbs lighter than when I started a few days ago, probably water weight), am just a hair under 6′, and am looking into what kind of lab-work I should have done to check and see the effects of what I’m doing. (Any recommendations on that front?). I’m also thinking about measuring the circumference of my waist, chest, thigh, arm etc. to estimate size changes, since it’s likely that I could be gaining muscle almost as fast as I’m losing fat. (Again, any particular recommendations?)
    Other info: I did a metabolic test, the kind where you lay on a stretcher and breath in a tube for 12-15 minutes, back in January. My estimated daily expenditure is 4832 Cals (3442 Resting + 1032 ‘Lifestyle’ + 358 ‘exercise’). I probably won’t do another one of those until Summer, or I’ve lost a significant amount of weight.
    I’ll try to keep this up for at least the month of March and let everyone know what happens!

  10. iIstarted the Fast-5 version of IF in September. iI had lost 15 pounds very slowly over the previous winter, but had been at a plateau since March (eating low carb) On Fast-5 i ate two large low carb meals in a five hour window. I ate as much in two meals as i had been eating in three. But something about NOT eating for 19 hours has had a profound effect on me. First, I quile easilly lost two pounds a week till I reached my present weight, which looks and feels good. I have been maintaining this weight since November on the same eating schedule.
    But perhaps more important to me than the weight loss is the fact that my moods have stabilized to a degree unrecognizable as me! And my sleep has improved remarkably as well. I experimented going back to regular eating and both sleep and mood went to hell….that was when I realized just how much they had improved with fasting. Since going back to IF I see even more improvement.
    I don’t think IF should be used as license to overeat carbs. That seems foolish. But based on my experience it is worth further study, because it does seem to help regulate some hormones.

  11. I’ve been IFing since last September. I gradually increased to 23/1 about 3 to 4 days a week. It’s controlled my need-to-watch-the-clock-to-know-when-to-eat syndrome. Cravings are gone. Binging is gone. Portion control is easier now.
    My health has improved greatly. I started out with hypertrophic cardiomyopathy. Now it’s negligible. Additionally, I am no longer borderline diabetic.
    I’ve done LC before without IFing but never had such wonderful results for my health.

  12. I think your feedback on IF is true in the following observations:
    – eating 1 meal a day of a ton of calories is not a good idea (esp when compared to 3 smaller meals)
    – IF is not a pass to eat anything (esp high carbs) you want and look like a supermodel
    – too much fasting can lower the metabolism
    – IF done the wrong way can result in no weight loss
    Although I also believe that there are so many variables to an IF lifestyle program such as:
    – Only fasting 1-2x a week to improve health parameters
    – Macronutrient ratios of foods during eating windows (carb/protein/fat)
    – Daily fasting windows of eating say Noon-7pm with 3-4 smaller meals
    – Type of exercise program that compliments it and nutritional recovery strategies
    I know myself that I have seen so many great benefits to IF for well over a year such as freeing myself from worrying about food all day long, reducing inflammation issues, being able to gain muscle and lose fat on less calories per day, and hopefully increasing my longevity. (If you believe in the CR studies that say less calories = longer lifespan) I am by no means starving myself or eating crappy foods. In fact I still eat a ton of protein and veggies and see great results in body composition and athletic performance.
    I think you will also see a large community of people doing high intensity exercise (such as Crossfit) and seeing great results as well.
    All in all, I do believe your observations mentioned at the top are correct. People still need to eat healthy and spread their meals out. I however also believe that IF is a flexible lifestyle choice and not just one set way, as there are tons of variables to change per individual’s goals and lifestyle.
    Keep up the great work on the blog!

  13. I have been following IF for almost 9 months. My my BP; after initially going up 10 pts has now gone below normal and my FBS, which I spot check, is now down from 115 on regular Atkins (3 meals) to 80 or 90 on IF. My lipids are the same as when I was doing straight Atkins (high, but a good ratio). My rotator cuff tear of 3 years has gone away without surgery and a ruptured disk I got in a fall healed in 6 days instead of 6 weeks. My body fat is lower, I have put on noticeable muscle even though I maintain ~170lb. I am male 72″ at 59yo. I seem to need less food per day. I could go on; the point is: I for one am staying the course for the health benefits. Note: I don’t always stay below 40 carbs, but I feel better when I do.
    I apologize if double post, I hve browser issues 🙁

  14. Hi Dr. Eades:
    This comment is about an unrelated subject. A friend who is worried about my low carb life style sent me this article from the Canadian Broadcasting Corp. (CBC) website:
    The article states that “Low-fat beats low-carb in diets to reduce heart disease” as if it were a done deal.
    I was wondering what is the relevance of reduced blood flow in the arms with respect to heart disease, and if this is the only parameter they measured, as they don’t supply a link to the research article. I find it hard to believe it holds as much weight as the huge drop in triglycerides and reduction of small dense LDL particles associated with low carb vs. high carb diets.

  15. I actually started IFing shortly after reading your blog last year. I stopped after a few months as I found it difficult to maintain my weight on a complete fast as I’m very active. Instead I now do a period of undereating/overeating where I would munch on berries throughout the day, which amounts to roughly 200-300 calories. And then in the evening around 9 pm, I would eat plenty of meat to get my calories in, usually after my workout. I believe this approach is consistent with what our ancestors did, I don’t think there were extended periods of time when they got 0 calories, even if they did not have a successful hunt. Having a small supply of glucose throughout the day minimizes gluconeogenesis, thus preserving muscle, but keeping the carbs low still keeps the body primarily burning fat. Ingesting that big meal after a workout also helps shuttle protein into the muscles when they need it most.
    I’m also a believer in food combining, while I think some vegetation is necessary to keep our bodies alkaline, eating meat separately from fruit had improved my digestion. Since I primarily eat meat and berries, this makes food combining easy. I should also mention that I’m big believer in raw foods being optimal, I only cook meat if not it’s organic/grass-fed.

  16. (Apologies if the links come out funny. I’m not sure quite how to squeeze them in)
    Two comments from other Tim Ferriss blogs, about losing 20 lbs of fat in 30 days (, and the other about gaining 34 lbs of muscle mass in 4 weeks (
    In gaining muscle mass, one of his recommendations is to “drop calories by 50% one day per week to prevent protein uptake downregulation.”
    In losing fat, he says recommends having a “dieters gone wild day,’ saying “paradoxically, dramatically spiking caloric intake in this way once per week increases fat loss by ensuring that your metabolic rate (thyroid function, etc.) doesn’t downregulate from extended caloric restriction.”
    In the past, you and Fred Hahn have stated in your blogs that carnivores don’t generally eat regular meals. They gorge when they make a kill, are almost completely sedentary for a while afterwards, then hunt again when they’re hungry.
    Looking over all of this (If there’s anything to the first two statements, I don’t know enough about Tim’s credentials for his statements, but have been familiar with you and Fred’s for years now), perhaps the appropriate method of ‘Intermittent Fasting’ is NOT a 24 hour rotating schedule, but should include at least one day of gorging, and one full day or two of true fasting.
    How long before your protein uptake truly ‘downregulates’ if you’re eating a steady diet of protein and low-or slow-carbs daily? How long before your thryroid function, and other metabolic functions ‘downregulate?’
    Just a thought.

  17. Let me summarize the months leading to my IF experience (to vent, and hopefully get some reader feedback):
    I have an underactive thyroid and thus have been monitoring it for the last few years and giving it hormone replacement therapy (this may have something to do with the results that follow)
    My old school doctor, wanted me on Statins because my calc LDL was 139 ( my HDL 43, TG 120) and TC was 206. I told him my thyroid levels needed to raise and requested prescription change (from 90 mg to 120) as my TSH was a high 4.3.
    Sure enough I lowered TC to 163, TG to 77, calc LDL to 106 unfortunately HDL down to 37 too. TSH came in low at 0.1 so I requested a happy middle 105mg. Fine.
    At this point, I started the intermittent fasting. As I said I kind of took the “you can even eat carbs” too literally, and had pizza…. one time I had cheesecake too. It became a eat what you want, as long as you stick to the schedule. I disregarded the “take the thyroid pill on an empty stomach, at least every other day” (on some mornings I was fasting). I started taking krill oil, and fish oil in large quantities (6 or so per day sometimes 8), and started taking vitamin D3.
    I came back to the doctor 2 months later. My TGs were 145, TC was a crazy 312, HDL 44, calc LDL 239, and TSH 24.3 Wow, what a surprise. The note with the results from the doctor was alarmist “You are at risk for a cardiac event such as a stroke or a heart attack” and it came with a prescription for statins. I was upset.
    I explained what I did with the thyroid pill not taking it during fasting, etc. So then I went back to low carb, to get these numbers under control, and religiously took the thyroid pill on an empty stomach thereafter. 2.5 months later TSH was normal (0.3), TGs still 144, Tot Cholesterol 297, HDL 46, Calc LDL 222. So really little if any improvement, again an ugly note with the results in the mail (don’t take advice from the Internet, etc type hogwash), with yet another statin prescription and a note to come in for free samples.
    I changed my doctor.
    I went to a new doctor in January, had the same tests done, TSH was 0.3 (good), Triglycerides down to 97 (wow finally an improvement), calc LDL 220, HDL 52 (another improvement) and total cholesterol still close to 300. This doctor referred me to an endocrinologist (thinking it must be the thyroid). So based on the recommendation to lower cholesterol (frankly I’m happy with more average results as my levels have never been so high), I suggested Niacin and the doc was fine with that. So I started on 1 gram a day, crystalline.
    So I go to the endo, my thyroid results look good (had a complete panel) and he figures let’s do a Direct-LDL because according to him it’s not the thyroid. Well it comes back at 225, TGs 99, Tot Chol 285 HDL a 42 (what happened to the 10 points?!). So he says increase the niacin. I am up to 2 grams/day. Vit D levels 25(OH)D3 are up in the 40s now (started at 25 in October). I do feel good.
    So I read Dr. Ravnskov’s recent article that says yes, young and middle aged men with high cholesterol do indeed have a high risk of heart disease. Perhaps this is hyperadrenalism from career stress, and the high cholesterol (which raises to protect the body) is sometimes not good enough to prevent the event. So great. now what? lol.
    My next step is to get a Liposcience test to at least see the particle size of the LDL. After that, possibly a CT heartscan, to see if there’s any plaque or other issues.
    Was the IF related to the experience? Correlation is not causation… any clues from readers would be appreciated.
    My next experiment (while remaining low carb with ocasional fasting), is to get some sunlight instead of the vitamin D supplements. Why? Well the body makes D3 from a cholesterol in the bloodstream. I’m thinking this may lower levels. We’ll see (along with the 2 gr of niacin).
    I’m also taking a baby aspirin, 1gr Arginine, CoQ10, many of the supplements in PPLP, and a multivitamin without iron (ferritin down to 66, one more donation to go).

  18. Dr. Mike,
    Just a question regarding Vlad’s post where he mentions food combining. This is a topic that has generated a bunch of brouhaha time and again. I know research has been conducted many decades ago by Pavlov. Food combining advocates suggest that fruit should be eaten alone. In your books, you are not averse to combining fruit, protein and fat in the same meal. Thus, i ask: is there any hard evidence that one should not combine fruits with animal products, and for that matter, nuts and seeds? I know that certain fruits such as berries and tropical fruits like pineapple contain enzymes that purportedly promote protein digestion.
    I don’t think there is any hard evidence at all that would recommend not combining various foods. Granted, I haven’t seen every study ever published, but of the ones I’ve seen, there isn’t any such evidence. I’m always willing to be proven wrong, so if anyone does have such a paper, send it along.

  19. So what I’m reading here in your update is that human studies show that eating a daily carb-bomb won’t improve insulin sensitivity? Duh!
    I never viewed IF as a way to get away with adding carbage to my diet.
    I am a very IR Type II diabetic. I first got interested in IF upon reading that it seemed to reduce blood sugar levels, improve insulin sensitivity and reduce inflammation.
    I’ve been doing LC/IF about 5 days a week for 9 months now. I eat all my food for the day in about a 2 hour evening eating window. I eat about 1400 calories, ratios of about 70% fat, 5% carb, 25% protein. I stick with nutrient dense whole foods as much as possible, with an occasional low carb tortilla or ice cream bar thrown in there.
    I’ve seen significant improvements in my BG. Spiking after meals was a big problem for me, the worse was after breakfast, which would often shoot up 50 or 60 points.
    Now that I don’t eat all day, my BG stays nice and low and flat all day. And since my glucose stores are very depleted by the time I do eat, I believe my muscles take it up better. I have very little spiking now after my one meal. Last night I was 101 right before eating, and 104 1 hour after I stopped eating.
    Dr Eades, you asked if we’re already eating low carb, why add IF? Here’s one answer. Although LC alone had greatly improved my BG levels, I was never able to achieve BG numbers as good as that through LC alone.
    When I began Low Carbing 18 months ago, I was a walking pharmacy on Actos, Glipizide, Lantus, and 1500mg Metformin. (Along with Lisinopril and Lovastatin). My A1c was still 11. Now it’s 5.2 and I no longer have metabolic syndrome.
    Now I’m off all the drugs except 1000mg metformin. I just went off the insulin 1 week ago.
    Adding IF to LC really has taken me the rest of the way in reversing my diabetes.
    I’ve lost 127 pounds in 18 months. I’ve calculated that for each 6 month period, I lost 15% of my starting weight for that period. So adding IF to LC neither increased or decreased my rate of weight loss. But it has improved my relationship and control over food. I think it will be a very useful tool as I begin maintenance.

  20. While I have not yet tried IF, I have been interested in trying it and would like to echo a few of the comments above. I think it is too soon to totally give up on the concept of IF. It is extremely hard to control for ALL possible variables. I wonder if controlling carbs as you recommend AND eating daily during a smaller window, say noon to 6pm would provide the benefits seen in animals but without the decreased thermogenesis etc. you write about. You could easily allow a later meal on occasion, or maybe just IF 2, 4, 5, days a week or whatever fit your lifestyle. I for one hope people keep experimenting with different regimens until they find one that is practical and beneficial for humans. Thanks for the update, but don’t give up the fight just yet!

  21. The parameters of the mouse CR study made me think of this alternate theory:
    It may be possible to accomplish a Calorie Restricted diet without unbearable hunger.
    What if the generally accepted ‘ideal’ proportions of protein/carbs/mono-fats/poly-fats/
    and saturated fats for lab rats (or even for humans) is wrong, and
    there are other proportions that can lead to better health,
    more longevity, lower caloric intake, and adequate nutrition, WITHOUT the extreme hunger.
    For example, the Yudkin study in the 60’s took subjects that normally ate
    an average of 2330 calories [84g protein, 124g fat, 216g carbs], and it
    changed their diet so that their protein was the same, their fat grams were
    reduced by 15%, and their carb grams were reduced by 69%.
    The Yudkin subjects then lived on this 1570 calories [83g protein, 105g fat, 67g cargs]
    without hunger, and their health and energy improved! And that is a 34% reduction in calories!! Voila, an instant CR diet.
    Many of us here understand these carb reductions will bring about huge
    improvements in health. So with a little supplementation of vitamins and minerals
    it may be possible to satisfy even much of the CR crowd that we are getting
    adequate nutrition.
    The biggest controversy in this theory is what is the ideal mix of mono-fats, poly-fats,
    and saturated fats for best longevity. I would trust Mary Enig to give us those
    figures, but I can’t find at the moment where she wrote those percentages.

  22. I started IF on December 31 last year after reading Brad Pilon’s e-book ‘Eat-Stop-Eat’. Pilon recommends two 23-hour fasts per week, from after-dinner one day to before-dinner the next, claiming that the benefits (lipolysis, growth hormone production, and so on) really begin to kick in around the 15-18 hour mark. He also recommends three resistance workouts a week, to prevent muscle tissue from being consumed for fuel during the fasts.
    At the outset, my weight was about 198 lb. at the time (I’m 6’1″), and all my blood indicators (cholesterol, triglycerides, blood sugar) were excellent, so I was hardly in terrible shape. I was eating a relatively low-fat diet, but not much processed food.
    Intermittent fasting was a revelation. First of all, I couldn’t believe how good I felt during the fast. From my early adulthood onwards, I’d had frequent low-blood sugar episodes (which had disappeared almost completely after I’d stopped eating large amounts of bread for breakfast), and I was wondering if I’d get the same symptoms on a fast–dizziness, headaches, cold sweat, inability to think clearly. Nope. Nothing at all. In fact, I felt more alert and energized than I had in a long time. I walk to work, and on the way home on my fasting days (after ~22 hours without food) I often felt like sprinting just to use up the energy I was feeling. That had never happened before. I was hungry towards the end of the fast, sure, but not for carbs, and not in that craving, need-to-eat-now way that I’d been used to. (Though I have to admit that diet sodas and sugar-free gum make it a lot easier to get by–they fill my need for flavour of some kind while on a fast.)
    Another fascinating effect that others have mentioned is the way that IF transformed my appetite. Before, I’d eat homemade muesli for breakfast, crave carbohydrates around 10am, then around lunchtime again, and then have a fairly large serving of starches with dinner. Now, I take only fruit, vegetables, and mixed nuts to work, and I find myself leaving bread and pasta to the side of my plate at dinner. (I usually have a bit, because I enjoy the taste, but not like before.) I am much more capable of distinguishing actual hunger signals from routine cravings than I was before IF, and the cravings themselves have actually gone down dramatically. (I still often crave sugar in the form of chocolate or ice cream after dinner, and allow myself that indulgence.)
    Since I had such a reduced desire for starches, I decided after about a month to go much more high-fat low-carb, and increase my fasting to 3x a week. This has also been a resounding success–I cannot remember when I felt so good and so alert, I am far less hungry than I used to be, and my much reduced food intake is made up of much more satisfying substances. I look forward to my M/W/F fasts, and love to break them with a good meal. (I believe that my success with the Eat-Stop-Eat method has been due to the fact that you eat dinner every day–a 30-hour full-day fast would be much more difficult to pull off.)
    I have to say, though, that IF hasn’t been much for weight loss, although that wasn’t my primary goal: I’m down to ~193 lb. from 198, and seem to have stabilized there, despite my much lower energy intake. However, Some of this will be lean muscle, since I’ve been seeing very good results with the Perfect Pushup program (currently at 120 pushups, 3-4 times per week, and soon to increase to 160). I have lost a substantial amount of fat around my midsection, gone up a belt notch, and several pairs of my pants are now too large to fit comfortably.
    I am eagerly awaiting the results of my next blood tests, due in August. Since my cholesterol and TG levels were already in the “excellent” category (my HDL might have been borderline TOO low), it will be fascinating to see if my new fasting plus HF/LC diet has done me any harm.

  23. In pointing to the Mattson study to debunk IF…how is eating one meal a day for 8 weeks straight any form of “Intermittent” Fasting? The results are not so shocking that one large meal spikes insulin daily and increases fasting glucose levels. That and what are the marconutrient ratios to what they ate? (high carb?). IF is not going to work if someone uses it as a pass to eat anything they want (which is probably high in sugar and carbs) in one setting every (or everyother) day.
    An unresolved issue in the field of diet and health is if and how changes in meal frequency affect energy metabolism in humans. We therefore evaluated the influence of reduced meal frequency without a reduction in energy intake on glucose metabolism in normal-weight, healthy male and female subjects. The study was a randomized crossover design, with two 8-week treatment periods (with an intervening 11-week off-diet period) in which subjects consumed all of their calories for weight maintenance distributed in either 3 meals or 1 meal per day (consumed between 4:00 pm and 8:00 pm). Energy metabolism was evaluated at designated time points throughout the study by performing morning oral glucose tolerance tests and measuring levels of glucose, insulin, glucagon, leptin, ghrelin, adiponectin, resistin, and brain-derived neurotrophic factor (BDNF). Subjects consuming 1 meal per day exhibited higher morning fasting plasma glucose levels, greater and more sustained elevations of plasma glucose concentrations, and a delayed insulin response in the oral glucose tolerance test compared with subjects consuming 3 meals per day. Levels of ghrelin were elevated in response to the 1-meal-per-day regimen. Fasting levels of insulin, leptin, ghrelin, adiponectin, resistin, and BDNF were not significantly affected by meal frequency. Subjects consuming a single large daily meal exhibit elevated fasting glucose levels and impaired morning glucose tolerance associated with a delayed insulin response during a 2-month diet period compared with those consuming 3 meals per day. The impaired glucose tolerance was reversible and was not associated with alterations in the levels of adipokines or BDNF.

  24. My husband has been IFing (though he doesn’t call it that) for most of our 30-year married life. No breakfast (other than black coffe), no lunch, and a dinner and dessert of typical high-carb stuff. The dinner/dessert period lasts around 2 hours, so he basically fasts 22 hours every day. (Not that he does this EVERY day, but most days.)
    So, for 30 years now, I’ve watched as he’s put on more and more weight around the middle. He’s actually in his 5th trimester now, or at least looks like it!
    IF might work for some people, but it definitely does NOT work for him.

  25. I am a type II diabetic who achieved good BG levels on low carb and even better BG on very low carb. But I still suffered from the dawn phenomenom. After a few weeks on IR with 2 meals per day and one meal per day at least once per week my 12 FBG went under 100 mg/dl for the first time. I also started experiencing flat BG curves after meals.
    For me the trick to IR is getting enough good quality fat in addition to adequate protein. When I get sufficient fat it is easy to go for a long time without eating. Every once in a while I will endulge in a high carb treat. But I have consistently found that even small amounts of grains cause problems. Going back to a consecutive high carb meals is another matter. It very quickly causes problems for reasons I will explain.
    Someone commented earlier that studies have found that IR decreases glucose tolerance. I assume they are referring to tolerance as determined by a glucose challenge test. This makes perfect sense. But in my opinion, it does not reflect a negative outcome. I came across an interesting paper on a study done years ago that compared GTTs done on one group of non-diabetics who had followed a low carb diet for a long time with GTTS of another group of non-diabetics who had followed a high carb diet for a long time. Guess what the results showed? The low carb group all showed a low tolerance to the glucose load challenge. According to the GTT they were all diabetics whereas the high carb group showed good glucose tolerance.
    Let’s think about this for a minute. We know that low fasting insulin levels are a key indicator of good health and further than high insulin levels are damaging. Low insulin levels are the norm. We also know that in theory the requirement for exogenous glucose and related sugars is zero. So it makes sense to expect the body to up-regulate insulin secretion when faced with an consistent influx of excess (which is anything more than zero) exogenous glucose and other sugars. So who’s glucose response is normal? The group on the low carb diet.
    This outcome is a graphic example of the absurdity of the current thinking on diabetes and normal glucose management wherein normal glucose curves are based on challenging subjects eating a high carb (read: high exogenous glucose) diet with an abnormal load of exogenous liquid glucose, a challenge that would probably never happen in the cavemen whose genes we all still mostly have.
    What some of us have found on IR is that our tolerance especially after a fast for a higher carb load is actually enhanced. This is not a contradiction, I suspect that the fasting period allows the insulin dump of phase 1 response to fully replenish. The insulin dump in phase 1 logically appears to be the first line of defense against a high load of exogenous glucose and associated sugars, in other words – carbohydrate.
    I agree with on the glucose tolerance issue, but in the Mattson studies the people following the so-called intermittent fast were not eating a diet low in carbohydrates – they were eating diets with a considerable amount of carb in them. The people eating high carbs while intermittently fasting were less insulin sensitive than those eating the same number of carbs only spread out through the day.

  26. Dr, Eades commented:
    “in the Mattson studies the people following the so-called intermittent fast were not eating a diet low in carbohydrates – they were eating diets with a considerable amount of carb in them. The people eating high carbs while intermittently fasting were less insulin sensitive than those eating the same number of carbs only spread out through the day.”
    Given that nothing happens without a reason, the outcome is still explainable. What seems to happen regularly is that someone takes a result observed with a high carbohydrate diet and then attempts to apply it to a low carb diet. For example, on the news this morning an MD reported on a new study that showed people gain less weight if they have breakfast. A few days earlier the same MD reported on another that showed that if one eats breakfast they will eat fewer calories during the entire day than if they didn’t eat breakfast. What is not mentioned is that this effect was observed on a high carb diet which fuels hunger. so the results are not surprising. The issue here is that metabolic evidence is continuing to amass that suggests that significant amounts of carbohydrate in the diet (which in some is not much) is toxic.
    Returning to the Mattson study, the fact that the subjects who were following IR on a diet with significant carbs ate the same number of carbs in a few meals as they ate when the same number of carbs were spread out during the day this would not have helped insulin sensitivity and/or cellular insulin resistance. For the same reason the advice of diabetes educators to eat 6 or more small high carb meals a day will give better blood sugars than several meals with same total carbs. However, this effect specific to carbs, one which ignores the real problem which is the carbs. It is a case of the lesser of the evils.
    I for one can not imagine even attempting IR on a diet with significant carbs. I overloaded on carbs only a few times over the Christmas holidays and it blew me out of the water for several weeks.

  27. Hi!
    Greetings from Finland and thank you for your blogg!
    I’m an born chronic. The first 40+ years were filled with all-year allergies and excemas. Then, I’ve been the last almost eight year finally symptomfree, thanks to lowcarb food. The “lowcarb” though is an elastic term :). With myself it has shifted from Zone to a more atkins-like LCHF and for the last 18 months to a sort of fasting with fat. So, now it is once a day meal loaded with natural fats. You may recall the polish doctor Jan Kwasniewski or his Homodiet? This comes closest to my present menu foodwise.
    In fall 2006 there were a group of Finnish lowcarbers, which tried IF after your blogg – one of us even contacted you then? Well, I did the 24/24 fasting for four weeks (it is even documented in the net, but unfortunately only in Finnish). Then my skin started to dry out, possibly because of too little calories or rather too little fat, so I stopped.
    However, since then I’ve been a LCFH evening eater and see no reason in stopping. My skin is finally full-time normal, my regularly blood lipids are excellent; and as a bonus, all flu’s at our house have vanished into plain air – or they stay away as long as my folks stay on this. Thanks to generous fats, we are not on restricted calories any more, yet my weight and waist have “normalised” to old sizes during this half-fast period.
    In our IF testing group at fall 2006 there were individuals that never felt well on partial fast and others who just naturally slipped in and have stayed on in, one way or another. One of the explanations seems to deal with abundant enough natural fats, but it does not explain the variation fully, either.
    If there’s anyone who still remembers JohnW and the zoneHome, greetings to them, too!
    Regards, LeenaS

  28. Dr. Mike,
    With regards to my previous post. After some thinking, i think the food combining issue is more relevant when one consumes starchy food. That is, protein digests in an acid medium, while startch in an alkaline medium. Thus, this combination may be most adverse in terms of promoting proper digestion. Indeed, back in my starch-eating days, i used to feel like s**t after eating a meal, for instance, of a roll with meat. Meat and fat, on the other hand, is a sinch, even if i don’t chew the meat all that well. I believe there is a paper that suggests that a Doctor discovered back in the Napeleon era, that meat doesn’t even need to be chewed and that it digests perfectly whole in one’s (human) stomach. If i recall correctly, the doctor placed a whole steak in a wounded soldiers stomach to see what would would happen, or something along those lines, and the meat turned to liquid in a short period of time.

  29. Dr. Mike, you’ve probably answered this a dozen times, but I’ll dare to ask it again. In a comment above, the poster David said, “When I get sufficient fat it is easy to go for a long time without eating.”
    Without being too anal about numbers, how would you define “sufficient” fat? In terms of percentages, is 60% fat sufficient? Is 90% too much? For example, let’s just take a 2000-calorie intake per day. At 60% fat, you would be eating 133 grams of fat; at 90% fat, you would be eating 200 grams of fat. Assuming no carbs.
    Could you give me some sort of ballpark? Thanks!
    I don’t know what a ‘sufficient’ amount of fat would be – I would guess it would depend on the individual. Let’s do the calculations on an 1800 kcal/day low-carb diet, a diet many people do very well on. Let’s assume we stick to 50 grams of carb – that’s 200 kcal, which leaves us with 1600 kcal to deal with. Most whole food low-carb diets contain about 25 percent protein, so .25 X 1800 give us 450 kcal of protein. Dividing by 4 (protein contains 4 kcal per gram) gives us about 112 grams protein, which is about right. Subtracting the 200 kcal of carb and the 450 kcal of protein from the 1800 kcal leaves us with 1150 kcal of fat. 1150 divided by 9 (9 kcal per gram of fat) gives us about 128 grams of fat. I would say this would be a sufficient amount. But I wouldn’t necessarily strive to get this much each day – just follow a whole food diet restricted to 50 grams of carb and let everything else take care of itself.

  30. “If I’m going to limit myself to low-carb foods, why go on the IF?” I think that’s rather telling—evidently you’ve never had any problems with emotional eating, or mindless eating, or other compulsive eating behaviours. Even low-carb grazing or bingeing can halt weight loss. For me, and a number of other people I know of, IF moderates those impulses. I can’t explain it; I just know that when that eating window is closed, I can pass up any food—low carb or not. The weight loss has been good, as well.

  31. David M said:
    ” I suspect that the fasting period allows the insulin dump of phase 1 response to fully replenish.”
    Brilliant. That must be at least part of the reason I can eat all my food for the day in one window and only spike up 10 points, whereas with regular meal eating I’d spike 30 to 60 points.
    Kathy said:
    “My husband has been IFing (though he doesn’t call it that) for most of our 30-year married life. No breakfast (other than black coffe), no lunch, and a dinner and dessert of typical high-carb stuff. The dinner/dessert period lasts around 2 hours, so he basically fasts 22 hours every day. (Not that he does this EVERY day, but most days.)
    So, for 30 years now, I’ve watched as he’s put on more and more weight around the middle. He’s actually in his 5th trimester now, or at least looks like it!
    IF might work for some people, but it definitely does NOT work for him.”
    Don’t blame IF, blame the carbs. Wheat in particular. Dr William Davis of the Heartscan Blog (hope I’m allowed to mention that here) calls it “Wheat Belly”. You may want to have your husband check out his blog, he’s a low-carb advocating cardiologist.
    This is the third time in 16 years I’ve taken off significant poundage (well over 100 lbs). But this is the first time I’ve done it through low carb. The first 2 times were high carb, low fat.
    This time, Low carb, is the leanest I’ve ever been. My waist is 9 inches smaller than my bust and hip measuremeants. And considering I did tons of exercise with the low fat attempts, and hardly any this time, there’s no question in my mind that getting the carbs out of the diet reduces abdominal fat.

  32. We were both approaching 50, and he had seen the scales move alarmingly in the wrong direction. With a strong family history of heart disease and diabetes, something had to be done. So, our adequate protein-low carb days began 5+ years ago. He quickly dropped 30 pounds, lost the GERD and blood pressure improved. He slacked off to Maintenance levels, re-gained 5 pounds and has been more or less content at about 15 -20 pounds above what would be considered an ideal weight. (Anxiously waiting for the new book to address the middle issues!) I lost the 10 pounds that had crept up on me since youth, and then a few more. I keep an eye on the scales to make sure I don’t go too low.
    Fall of 2006, he was involved in a MVA which resulted in a period of forced inactivity, and the pounds started to sneak back. About that time, the famous IF post caught my attention, and we decided to give it a try. We started with the 6pm – 6pm schedule, but have since modified. We eat dinner every day, then fast until late afternoon on alternate days. This results in a fasting period of 20 or so hours on average. Recently, he has started to eat a high protein meal earlier so that his fast is more like 16 hours, basically a daily schedule of eating during a 6 or 7 hour window. Although he is about 70 lbs heavier than I, he was eating about the same amount of food. He is quickly sated, and has a hard time ‘stuffing’ in adequate protein in too short a time, then is hungry later. We’ll see if this works better. Come to think of it, this is a return to what is historically a more normal routine for him, he never was a breakfast eater.
    Fasting is definitely not a license to over indulge in stuff that is just bad for you, whenever you eat it. That said, we do lighten up on strict carb counting, we enjoy some higher carb veggies, and maybe some fruit. We blissfully sip the dry red wine with dinner, and savor the two squares of very dark chocolate after. And yes, sometimes indulge in a ‘real’ dessert for a special occasion. We never, ever eat bread, pasta, potatoes, rice, any processed foods or diet drinks. I have recently gone gluten free to see if I can head off the beginnings of arthritis in my hands (already suffer from Raynaud’s and Dupuytren’s. Don’t need any more hand diseases!)
    So, musings on our fasting experience …. We like it. It’s easy to maintain and does free us from counting those carbs quite so diligently. A few months in, he did see a rise in blood pressure. We cannot attribute it to diet as we were hit with some major ongoing and unavoidable stress at the same time. Weight is stable for both of us, although we had expected him to lose more (OK, maybe he indulges in those goodies a little too often, or maybe it’s the sugar free gum, or maybe he’s just not eating enough????) Besides the scales and BP (mine is very low, his is high-normal) we have no concrete indicators of what may be happening such as increase in insulin sensitivity, blood sugar etc. We know we feel great and haven’t been sick in ages.
    I’ll echo what others have said, it’s too early to totally trash the idea. More studies need to be done controlling for some of the many, many variables. I would be interested to hear if some of those bad numbers were reversed when the subjects resumed a ‘normal’ eating schedule.

  33. Here’s where I get all mixed up with what’s the difference between glucose tolerance and insulin resistance. If I am IR, isn’t it expected that I would react badly (insensitivity) to carbs? If I don’t consume high carb foods, my glucose stays low, hence is not my insulin also low? I’m confused and it’s entirely possible (and probable) that I’m just too uniformed.
    I am only on my 2nd week of IF doing the protocol Dr Mike set up. I’ve had a few instances of eating too much on my eat days, but I do beautifully on the fasting days. My FBG was in the low 100s before IF and I’ve had some instances of 83-86 these days. Most FBGs are in the low 90s and i fully expect to see continued improvement. I have weight to lose, but I haven’t weighed to see if that is happening. But what I have noticed in just this time, is my pants are loosening. Something good is happening!
    My first thought when I saw this article was to jump off the IF bandwagon, but I think it’s premature. My glucose levels are lowering nicely. How could that be bad?!
    People can be insulin resistant yet not glucose intolerant. If it takes a you lot more insulin to regulate sugar than would be required for a person with normal insulin sensitivity, then you have insulin resistance. But you may not be glucose intolerant…yet. Why? Because your excess insulin is keeping your blood sugar where it is supposed to be. If you are glucose intolerant it means that you probably are insulin resistant as well. But it could also mean that you aren’t producing enough insulin, i.e., could be in the early phases of developing type I diabetes, a condition much, much rarer than insulin resistance.
    If you are doing well on an IF, don’t let my article dissuade you. Some people do very well on the IF regimen. But some don’t. The only way to know is to give it a try. My point was that IF isn’t the universal solution many people thought it was going to be several years ago. Some people do develop problems.

  34. MizKitty, I do blame the carbs, not the IF. I only mentioned it because in Dr. Mike’s first blog on IFing last year, he said you could even eat high-carb during your feeding window and still reap the benefits of weight loss. In fact, he started out the post with these words:
    “How would you like it if I told you there was a way to eat pretty much anything and everything you wanted to eat and still maintain your health? Or better yet, what if I told you that you could eat pretty much anything and everything you wanted and even improve your health? ”
    He went on:
    “There is a way to reduce blood sugar, improve insulin sensitivity, reduce blood pressure, increase HDL levels, get rid of diabetes, live a lot longer, and still be able to lose a little weight. All without giving up the foods you love.”
    He said that it’s BETTER with low-carb foods, but you get the benefits with high-carb foods also.
    All I said is that this doesn’t work for my husband.
    Oh, and thanks for the link, even though DH would never read it. Over the years I’ve tried to get him to read Protein Power and Dr. Mike’s blogs, but he’s a stubborn one!

  35. Thank you, Dr Mike, for the clarification.
    I haven’t been diagnosed anything, but I suspect at least IR at this point. I had two diabetic pregnancies and tons of family members with diabetes. Eating stictly low carb has not lowered my glucose levels as much as one would think, even when I tried Metformin. But the fasting has helped. I will try to keep eating LC when I eat (and not do the free-for-all carb stuff) and see what happens over a longer time trial than just 2 weeks.
    Anyway, thanks a bunch for the info. CHEERS! 🙂

  36. David MacPhail said:”For example, on the news this morning an MD reported on a new study that showed people gain less weight if they have breakfast. A few days earlier the same MD reported on another that showed that if one eats breakfast they will eat fewer calories during the entire day than if they didn’t eat breakfast. What is not mentioned is that this effect was observed on a high carb diet which fuels hunger. so the results are not surprising.”
    I’m rather confused about the relevancy of your comment regarding high carb diet fueling hunger to these two studies. I agree that HC does fuel hunger and I agree that the results of the two studies are no surpise and support each other, if one eats fewer calories then one should (according to the calories-in, calories-out theory) gain less weight. My experience has been that if I eat breakfast it sets me up to munch and snack throughout the day so I end up eat more calories, even eating a low carb breakfast does this.
    I have been giving IF a try for the past month or so. I have been having trouble losing the last 10lbs of fat. Every time I have dieted and reached this point I experience decreased thermogenesis to such an extent that I get tired of being so cold all the time and give up. I have had the same experience as several others have mentioned, it has freed me from emotional eating and now I only eat when I’m truly hungry and not because my blood sugar crashes or I’m upset or bored.
    I have never liked eating breakfast, at least not until I have been up and around for at least 2 hours. So, using this and my current work schedule as my basis, I fast from 12-18 hours each 24 hour period. I have set a 9pm food cut off and try not to eat again until noon the next day. Because I work evenings, I often eat dinner before 5pm and then nothing else except maybe a square of Ritter’s dark chocolate. I have eliminated grains from my diet and severely restrict potatoes. Around noon I will eat something low carb/high fat like walnuts, eggs with cheese and/or ham, sugarless custard made with whole cream, or crustless quiche. Between 3 and 6:30 I’ll eat a low carb dinner usually some sort of meat and lots of vegetables. Then, on days I feel cold, I’ll up my calories and carbs with whole milk yogurt, hot cocoa made with ½ whole milk & ½ whole cream, Haagen-Dazs ice cream, pork rinds with cream cheese and/or fruit still keeping my carbs below 100gms.
    So far my results have been promising. I’m finally beginning to lose that lower abdominal fat that I could never get rid of before. My blood sugar is stable unless for some reason I eat some grains. Oddly enough eating the amount of sugar in a half cup of Haagen-Dazs doesn’t seem to affect me as much as eating a half inch slice of a baguette.
    I live in a city so I walk everywhere. I probably walk an average of 2 miles a day.
    In nature everything works in cycles. I think this is true for the human body too. It seems to make sense that IF works by cycling back and forth between periods of insulin release and glucagon release with all the attending effects of each. For example, there will be periods of inflammatory responses and periods of little inflammatory response, periods of fat burning and periods of fat storage. I guess what I’m trying to say and not very well at that, is that the body has evolved to be cyclic, the standard diet keeps things relatively static resulting in too much of one part of the cycle and not enough of other parts. It may be that IF must be accommodate to each individuals circadian rhythm, to seasonal rhythms, and in the case of women, to monthly rhythms. This is where looking to our Paleo past helps to show us our natural rhythms that are being disrupted by modern life.
    Sorry that this got to be such a long post. I look forward to reading more peoples experiences with IF.

  37. In Dr. Johnson’s/Laub’s asthma study, blood glucose did rise about 5%, but insulin levels dropped 13% and one marker of oxidative stress sunk clear out of sight. Their regimen included 500 calories on the down days. Maybe this more moderate approach is preferable.
    Dr. Johnson actually refers to the Mattson study finding that oxidative stress is not reduced on a one meal per day regimen and recommends spreading out the consumption of about 20 to 50% of normal calories on alternating down days.
    Also, how important is slightly higher blood glucose if oxidative stress is dramatically reduced?
    The Johnson study didn’t include blood pressure data and doesn’t directly refer to the blood glucose rise on his website.
    I don’t know the answer to the question on blood sugar and oxidative stress. Elevates blood sugar causes problems, of that there is no doubt. But birds have much higher blood sugar levels than do mammals of a comparable size, yet outlive these mammals by many, many years. Why? One reason is that birds can more easily decrease the proton motive force across their inner mitochondrial membranes thus uncoupling respiration from oxidative phosphorylation, and in the process they produce many fewer free radicals. But how to we do the same? That’s the big question.

  38. I am undecided on IF, at least for obese overweight people for two reasons. One is that lowering metabolism more seems counter productive? But also, because I have known a few low carbers whom have tried IF whilst low carbing (not high carbing) and failed miserably with it leading to binging. I remember one lady whom seemed to be doing well for a while and then she started getting preoccupied with food and I remember an account by her where she threw up in her sleep. These same people had the same type of issues following diets like kimkins.
    Then there have been accounts of others whom were obese/overweight doing fine with great stories like Miz Kitty. Maybe it is more a YMMV thing?
    In regards to Miz Kitty (not to take anything away from her great results!) but I was pondering something in regards to her metformin use. I remember reading a few years back on a science and supplement based body building forum about the protective qualities of metformin during calorie restriction and I was wondering if that could be helping her results?

  39. Another pitfall of the daily fasting regimen is elimination. If you are only eating one big meal per day, you only have one big elimination per day. The hemorrhoids caused by this were another reason I went to back to eating more meals per day.

  40. Reading the posts by those who have experienced a profound improvement in their health on low carb and IF has caused me to think critically and deeply about energy systems in the human body and especially the use of glucose. In view of this, it seems reasonable to posit that the normal use of glucose is in a closed (endogenous system) with glucose being produced as needed through the process of gluconeogenisis. In other words, the body has no need for exogenous sources of glucose. This is supported by the fact that the only macronutrients required for health are protein and fat. In this closed system the production of glucose is tightly regulated as evidenced by the lack of any need for a first phase (insulin dump) response.
    The problems arise with exogenous sources of glucose because of the inherent difficulty in controlling the quantity and especially the glycemic conversion issue. To have some degree of control the body would need a first line of defense against a large influx of exogenous glucose. The insulin dump is the macro control mechanism. It is reasonable to assume that the capacity of the insulin dump repository (IDR) is limited by the influences of evolution. If man did not eat high carb loads and the conversion to sugars was not rapid then the capacity of the IDR would not need to be large. According to the rules of evolution the IDR would develop according to need.
    Although the capacity of the IDR would be greater in some than in others it is doubtful that in most it would be anywhere near adequate for the carb loads and rapid release of exogenous glucose that modern man (and women) are experiencing and especially the frequency of these loads. The best information I can find is that in a healthy person (whatever that is) it takes about 5-6 hours for the IDR to replenish if the pancreas is free to secrete insulin specifically for this purpose.
    If the above hypothesis is true then the effects of a single high carb meal could easily overwhelm the insulin dump with the result that BG levels would rise too high even as glucose continues to be released from the digestion of carbs. The only option I can see for the body is to up-regulate the secretion rate and mount of insulin. If not immediately, it seems obvious that over time it would become increasingly difficult to fully replenish the insulin dump repository. After a sustained period of high carb eating, especially frequent eating of high carb meals the BG management system may never have an opportunity to replenish the repository unless — we stopped eating.
    A steady diet of high carb meals could initiate a cycle where the only option the body has to deal with high BG levels is on demand insulin secretion which would probably not be adequate to maintain BG within healthy levels. So what happens next? The cells develop insulin resistance to try and stop insulin from initiating glucose transport into the cells. In other words the cells must now attempt to defend themselves in what amounts to one on one combat with glucose.
    Obviously, there are a lot of questions that still have to be answered in my theory. But there are some very bright people in this forum who are capable of arguing either for or against this theory which is an attempt to move past the low carb vs high carb arguments and get to the what I see as he meat of the issue namely that the body has two very different glucose management strategies and the focus to date has been on portraying the glucose defense process as representing normal blood glucose.

  41. I’ve been IFing since right before the Xmas holidays and man did it make a difference. I had been doing resistance training since last May, but still eating poorly. I made slow gains, but when I added fasting the progress picked up tremendously and suddenly in a matter of a couple of months I’m about half way to where I need to be. I’ve gotten off a couple of medications, my BP has come way down, and most particularly, the fasting has radically altered my appetite and given me real high-resolution, i.e., I don’t seem to crave food when I’m not particularly hungry. And, a bit of hunger has actually become a pleasant feeling rather than a gnawing feeling.
    Anyway, here’s my progress in pictures:
    And here’s some of my posts specifically dealing with my fasting experience, in chronological order. As you might notice, it has been a bit of an evolution for me.
    And if you’re not inclined to wade through all that, and I wouldn’t blame you, what I basically do and how I approach it is to put myself into what I call an “evolutionary state of hunger.” So, basically, I’m fed until I decide to stop eating and then I go for periods of 24 on up to 36 hours before eating, but I always polish off my fast with a very intense full-body resistance workout at the gym. Curiously, even if I haven’t eaten a thing in 30 hours and have a pretty deep hunger, 10 minutes into the workout and my appetite is completely killed, and hunger does not return until about an hour or two after the workout.
    It’s pretty much working out to two fasts per week, 30 hours each. I have found that lunch to dinner next day is actually far easier than dinner to dinner. I think it’s because by bedtime you have skipped dinner and so are hungry and during sleep your body better prepares you for the hunger. I wake with no hunger at all, and it’s pretty easy to take until dinner the next day.
    Hey Richard–
    Thanks for the photos and links. It’s all pretty inspirational. I congratulate you.
    Keep up the good work – you’ve obviously found something that works for you.

  42. Dear Dr. Mike,
    I was intrigued by your earlier posts on IF and decided to experiment around with it.
    I have borderline severe hypoglycemia (according to a 6-hr. glucose tolerance test),
    so I wanted to see how I could do the IF and maintain blood sugar control. Because I don’t quite have the nerve to go totally without food – severe blood sugar drops
    are NOT fun, I started with a solid breakfast of high protein and a couple of fresh apricots (about 10 gr carb – around 600-700 calories); then I went to a job and observed how long my body would take to get really hungry. The first day – 6 1/2 hours! The second day – 7 1/2 hours!! I was in shock.
    For 30 years, I’ve been very careful to eat 5 or 6 smaller meals a day and to carry around some kind of snack in case my blood sugar went too far south. Anyone with hypoglycemia will know exactly what I’m talking about.
    The down side is that even I – who really loves food – became annoyed with having
    to eat all the time. I felt shackled to kitchens and grocery stores. It may have been
    a “pleasant” slavery, but slavery is still slavery.
    IF, in the modified form, has set me FREE !!! As long as I am ruthless about keeping the carbs below 30 grams, I can eat 1 meal a day, or 3, if I want to. Recently, I went
    22 hours on about 700 grams of food in 2 small meals close together. And I lifted weights on the same day. The morning after, I put down a large burger and a huge bowl of vegetable soup, but didn’t eat again until suppertime.
    The ” heavy eating” days vary a lot; sometimes I clean out the fridge and sometimes I eat just moderate meals at the usual times. The light eating days seem to average out at 2 days a week, but this timing is not written in stone.
    I don’t know how my blood values, et al, are responding to all this, but I’m elated.
    Regaining some Freedom, even if it’s just freedom from the pantry, is FANTASTIC.
    That’s got to create good effects in ways I don’t even know about !!

  43. This just posed from Baylor University. Can IF be finding acceptance in the mainstream world?
    Single-day fasting can have benefits
    March 6, 2008
    “Recent health studies show that those who fast for 24 hours at a time are more likely to have a healthier heart arteries and pancreas.
    Throughout a fast, the body is forced to use fat reserves to burn calories. During a normal food diet, a person’s insulin-producing cells activate in order to metabolize sugar intake. A diabetic’s insulin-producing cells are less sensitive to food intake than normal insulin-producing cells. So, fasting gives the insulin-producing cells a break, letting the cells become sensitive to sugar again.”
    In an earlier post Terry asked about the relevance of my comment on high carb meals fueling hunger. He said “My experience has been that if I eat breakfast it sets me up to munch and snack throughout the day so I end up eat more calories, even eating a low carb breakfast does this.”
    The reason I mentioned the reports on the so-called studies that purport to prove that breakfast is the most important meal of the day has to do with what I call ‘The Power of Normal’. There is tremendous social pressure to ‘be normal’. Any party who controls the public perception of ‘normal’ possess tremendous marketing power and political clout. It is studies such as the ones I cited that influence people to believe it is normal to eat breakfast, that it is normal to be hungry after a few hours, that it is normal to eat 5 – 6 or more meals per day, snack non-stop, ad infinitum – to which I would add “only if you are eating a high carb diet”. What these studies do is create a facade that high carb eating and the effects of high carb eating are normal, desirable and even necessary for good health – implying that it is the way we were intended to eat and have always eaten since we first crawled out of caves. In this paradigm, low carb and IF are abnormal, even dangerous.
    I invite anyone who thinks that high carb diets produce ‘normal’ blood sugars to view the slide show presentation (available online) from the International Symposium on Diabetes held in 2007 called ‘What is Normal Blood Sugar’. If this presentation doesn’t convert you to low carb and IF after the first viewing then nothing will. The study, which used continuous BG monitoring, showed that the highest BG spikes occurred after a morning meal. The reason Dr. Bernstein recommends that carbs be kept very low at breakfast is that if BG spikes then it sets the pace for the rest of the day. For this reason I no longer eat my firsts meal until at least 11 AM.

  44. So IF might lead to the holy grail of SIRT1 gene expression for some, but not all. Or even that’s a reach?
    It’s possible.

  45. Here’s my IF experience: I tried strict 22/2 IF (very low carb) for several weeks. I was a little surprised (and gratified) to find out that yes I can go without food for fairly long times while keeping stable blood sugars, but I sure could eat when I “opened the window” – sometimes close to 1500 kcals in a single hour! (I’m a fairly small woman). I would also start thinking constantly about food and what I was going to eat in the hours before this event. Is this binging behavior? I’ve never had that problem before, and I was getting a little concerned.
    The other problem I had was after a few days of IF I just wouldn’t want to move much… for instance I went hiking with friends and although I felt fine I found myself just standing or sitting whenever they stopped for some activity… my body just naturally ceased all movement until it was necessary to move again. No extra energy for running around. I began to worry that my body was conserving fat and my metabolism was dropping.
    My daily calories usually averaged a few hundred lower than usual (without IF) but I didn’t see much difference in my weight from it, so I finally just stopped doing that. I guess IF didn’t work out so well for me.

  46. Dear Dr Mike,
    as for the adequate fat, the system that seem to satiate me is on higher regimen than your 128 grams. My carbs seem to stay without an effort at around 50g, as do my proteins. And this is for a small lady doing science at the office all day, not exercising much at all, and turning to be 50 this year. Yet I eat 150-200g of fat daily.
    Mainly the fat comes from milkfats and organic pork fat, but some comes also from nuts, other animal fats and small amounts of canola in salad dressing or mayonnaise. The choice of fats is partly dependent on living up north, where these are the native resources (well, nuts are present but scarce); olives do not grow here. And partly the choice is due to my being allergic to fish all my life. When starting on restricted carbs at summer 2000 I tried and succeeded in supplementing with fish or cod liver oil; but after a couple of years it just made my blood too runny, so I stopped. (B.t.w, my latest measured lipids with these killer fats were HDL/1.9, LDL/2.7 and trigs 0.6, on the European scale)
    I know a couple of others who seem to be thriving on similar macros and on evening meals. Yet only after falling into this and calculating the values I noticed that this is actually very similar both in quantity and in quality to the Kwasniewski diet. His p-c-f grams are 1 : 0.8 : 2,5..3,5 in terms of grams per maintenance body weight. And he treats with his diet diabetes and other chronic conditions more than overweight. Neither are my macros far from the Annika Dahlqvist treatment on diabetes-2 (who just got “a full pardon” from the Swedish government, aften an official complaint and an equally official scientific inspection 🙂 Hers are 10% carbs and official 10-20% of protein, rest being fats.
    So, you might not have heard, but by now there are actually two countries in the world with the acceptance of authorities to treat diabetes-2 with LCHF: Sweden and Poland. Finland may unfortunately be the last one to succumb, thanks to Keys and the North Karelia project… Which is sad, since the North Karelia project actually showed that Finland had even at that time females with just about the highest total cholesterol levels AND just about the highest life span in all Europe. (You may not have heard of this, either, since this finding got somehow lost in international reports – yet is is reported in a scientific paper, at least in Finnish)
    So I’m thriving on higher on fats and lower proteins than most paleo diets recommend. Yet who knows? Here up north the winter conditions have always been very fat-favorable. And the same conditions and huge seasonal changes seem also to fit well with alternating feasting and fasting 🙂
    LeenaS from Finland

    Hi Leena–
    Thanks for the nice letter. Actually there may be three countries with ‘official’ acceptance of the low-carb diet as a treatment for type II diabetes. This year the American Diabetic Association approved the use of low-carb diets in the treatment of diabetics. The approval was luke warm, but it was there.

  47. With regards to Iris’ post, i strongly feel that IF promotes binge-eating behaviour. I’ve frequenlty heard people say that when they fast intermittently, they constantly think about food. Also, many people eat so much in the eating period that they become almost dormant. Indeed, when it tried IF, i became almost reclusive, in that my evenings were planned around “re-fueling” and when i ate i ate to the point that i didn’t feel like doing much else but panning out infront of the TV. As a final thought, i still practice IF, but in a very relaxed manner, in that i fast a few times a week if i feel like it. For instance, today and yesterday i didn’t have breakfast, only water and black coffee. Last weekend, i was pretty active on saturday and so i forgot, or rather didn’t feel like, eating at all during the day. The rest of the week, however, i ate more regularly. In short, my experiences with IF are similar to those of the Drs. Eades, in the sense that, yes, i’ve learned that i can go without food for periods of time, and therefore will skip meals here and there, but find it simpler to just eat more regularly, instead of abiding by some meal-timing schedule.

  48. Iris, did you go from a high carb diet to a VLC diet in one jump? if so, this could be your problem. It seems to me that many (including myself) who have had excellent results with IF went through a fairly long carb reduction process before we tried IF.
    Perhaps Dr. Eades can offer some insights on this. But I think some period of metabolic adaptation may be required especially with regard to BG management because the evidence I have seen suggests that the body adjusts to carb loading.
    In my experience most of the patients I’ve treated haven’t had a problem with a drastic carb restriction.

  49. For the life of me, I just cannot figure out why the Drs Eades, prominent LC DOCTORS AND AUTHORS, didn’t test the IF premise on themselves following PP PRINCIPLES. I mean, come on! That is the study that needs to be done! Even a study of 2 people would have been helpful! Why would people who stand for PP as the best and optimal diet for all mankind test a method to see if it allows for high-carb eating? I would have much more interested to hear how LC IF might affect a LCer.
    As a long-time LCer, it never occurred to me to use IF as an excuse to eat more carbs! And Dr Eades comments on 9/13/06 and 9/19/06 led me to believe that they were of the belief that a combination of PP and IF is most likely the OPTIMAL way to eat. I am in search of optimal health and weight MAINTENENCE, not some reason to eat junk and get away with it. Now, after IFing for a while, and in the process of smoothly making a transition to one meal a day, I’m concerned that I’ve done some damage to my body and my metabolism by IFing and LCing. Great.
    I don’t think you’ve done any damage to your body by IFing and LCing. I LC all the time, but like most people, I would love to be face down in the carbs. I looked upon the IF as a way to allow me to loosen my normal carb restriction. I’m in good health and keep my weight in check with the LC diet on a regular basis, so why go on the LC diet on an IF basis if I don’t need to?

  50. My pet peeve response from people looking for an excuse to NOT change their eating habits ……… “Well it’s OK and it works for you, I guess, but we’re all different you know.” How do they know how ‘different’ they are if they refuse to ever try?? Grrrrr!!!

  51. You know, it seems to me that a lot of the problems people are having on IF are specific to the 22/2- or 20/5-type regimens, where you only eat in a small window every day.
    Folks, everyday fasting is hardly “intermittent”. I’m no doctor, but it’s hardly surprising to me that if you fast every day and only allow feeding in a small window you’ll start to crave food and experience a slowdown in your metabolism.
    “Intermittent” implies to me that the fasting should occur with intervals between, allowing your body to restock itself and not get bogged down in a daily no-food cycle. Ideally, you’d make it a somewhat stochastic process–one day interval, then three, then one, then two, and so on–just to make it a truly unpredictable thing, and perhaps somewhat more like our ancestors’ experiences. But that’s tough to do with a modern schedule, so I fast on Mon/Wed/Fri, about 7pm-6pm. It works really well for me: as I said above, I experience no cravings, don’t binge-eat at all when I’m not fasting (in fact, it seems to have reduced my appetite), and experience an actual increase in physical energy and mental sharpness.
    Perhaps the daily fasting regimens should be called DF to distinguish them from IF.

  52. I wanted to thank you for your response to my rant. It does make me feel better to hear you say that.
    I like LC/IF, a loose version for me at 18/6 or 20/4, with a snack to break~fast and a large dinner, because it satisfies some weird emotional need I have to get comfortably “full” once a day–preferably in the evening. I was not able to achieve the same emotional satisfaction with the diet, eating 3 smaller meals a day. Plus I find that if I eat to satiety once a day, I can’t really eat again and not be overeating. So it happened kinda naturally.
    LC/IF frees me from that “standard” of having to eat 3 times a day, too. So it meets a lot of needs for me, more emotionally than anything else, I guess. I don’t think I could go back to eating 3 times a day anyway…whenever I do, even just 2 small snacks and dinner, with the same overall food intake, I feel bloated and gross., just from breaking fast early. I guess my gut is used to all that “rest time.”
    Perhaps it hearkens to my Paleo roots–that when they ate, they tended to eat a lot? With LC/IF I can satisfy that need, and feel good about it

  53. I started IF when you first blogged about it. I started off following an every-other-day schedule (cut-off at 6pm, eat dinner next day at 6pm). I’ve had some issues around food/eating, namely a real fear of being hungry or going without food for too long. At first I struggled with those issues, but as I got used to it I realized that I just wasn’t hungry in the mornings…and that was ok.
    Eventually, I found that a truly intermittent “schedule” worked best – I eat when I’m actually hungry. Usually, that’s not until late afternoon, say around 2-3pm. Some days it’s later – other days, it’s earlier. IFing helped me learn the difference between the urge to eat (boredom, stress, entertainment etc) and needing to eat (hunger). That alone is worth it to me. Being comfortable with waiting to eat has really given me a psychological freedom I didn’t have before. I used to bring food with me everywhere – now I am fine without. I know I can wait.
    I also learned when I am full. This was a HUGE step for me. At first I’d eat huge meals, justifying it bc…well, I hadn’t eaten all day. I’m a small woman – 5″2, 113lbs (and losing) – but I can out-eat a football team if it’s a food I enjoy. Feeling stuffed equaled safety and security for me previously, but now I am comfortable eating until I am sated. I can tell now when my body is saying “enough”. Low-carbing alone didn’t set that straight. The first time I stopped halfway through a butter-soaked ribeye because I’d had enough was astounding to me!
    For someone with compulsive eating tendencies, used to 5-6 small meals a day and constant grazing, IF has been a lifesaver.
    Hi Tracey–
    Thanks for the informative comment. IFing actually helped me in the same way. The first time I was able to push away from a steak and leave about a third of it unfinished, I was amazed.

  54. I began IF last year after gaining 30 lbs. I was strictly low carb for 5 years. I had lost 30 lbs. initially. Then, probably due to perimenopause. I began to gain weight. I did tweaks here and there and nothing worked. Nothing worked until I read about IF. I began to realize that 3-4 meals a day was probably not giving my digestive system a rest. I don’t know. But, after doing a series of 20 hour fasts with a 4 hour eating windows, I began losing. I weighed 166 lbs this time last year. I now weigh 149 lbs. Now when I break my fast, I eat like a pig and I eat as much food as I can hold. Then I may nibble but usually I will not even be hungry by dinner time. But I do eat at this time since we all sit down as a family. I IF in this manner mostly but sometimes I do it differently. For example on Saturdays, because of my work schedule, I will break my fast in the morning but I don’t eat again until dinner time at around 6:00. Some days I will have only 1 meal. I add coconut oil to my coffee in the morning to keep my stomach from growling. It really helps the comfort level as my fast approaches the 20th hour. 🙂 I have milder periods and less cramping during that time of the month. Also, doing low carb has helped lessen the pains my achy joints. But doing IF has finished the job. I do IF totally low carb with a cheat of maybe 1 or 2 girlscout cookies. It definitely is working for me.
    I’m glad to hear the IF is working so well for you. Keep up the good work.

  55. I want to add more. I didn’t finish my last post because I had to leave for work. One thing that I experience after breaking my fasts is a healthy BM within the hour after eating. I credited this with the concept of allowing food to completely digest which could possibly enhance peristalsis. That alone is worth doing IF, IMHO :-). Although I do not know what my insulin levels are but they “feel” normal. I have not experienced a pike at all and I have been doing this for nearly 1 year. I notice also that when I go to the Curves facility, my body is beginning to show results, finally. Sooo, my fast is not as strict as a true IFer since I basically eat 2 meals a day. But, my concept is the same and I enjoy doing it low carb. I , no doubt, eat fewer carbs than before although I try and keep the caloric intake the same.

  56. Dear Dr Mike,
    I did try IF for a while but I did not settle with it. I did not feel great on it (marginally type 2 diabetic). It may have been my nutritional type which tends towards being a carb type.
    Are you familiar with the work of Byron J Richards “Mastering Leptin”? (Just in case you are not, there a five basic ‘rules’ for his ‘Leptin Diet’ 1. Never eat after dinner, allow 11-12 hours between dinner and breakfast. 2. Eat three meals per day with 5-6 hours between meals. 3. No large meals (!). 4. Have a high protein breakfast. 5. Reduce the amount of carbohydrate eaten.)
    To me, these rules are very much in sympathy with both the philosophy of IF (5-6 hours can be a long time!) and the need to reduce carbohydrates.
    I would be interested in hearing your opinion of Richard’s work. Is this the ‘middle way’ between full blown IF for furry animals (by the way, my cats aren’t impressed!) and the different needs of humans? Is it maybe as we humans consume huge amounts of energy using our brains, we naturally need more fuel than the furries? Your younger correspondents may not be so effected by the age aspect but in older people the effects are probably different?
    I’m not familiar with Byron Richards’ work so I can’t comment intelligently. There are so many variations of the IF that it’s difficult to make recommendations that cover all these iterations. If you have problems with it, I would try a different variation or abandon it entirely.

  57. I’d like to IF. Even sticking to LC, I’d prefer IF. Dr. Mike, you keep asking why IF if you’re LCing anyways – this would be a reason for some folks! My “natural” eating pattern is to not want breakfast except for coffee, often skip lunch and then eat in the evening from dinner to bedtime. When I first read about IF, I thought the idea was wonderful that it could be healthy, especially something like the fast-5 protocol, which is pretty much what I naturally want to do anyways.
    Unfortunately, after 2 decades as a diabetic, I can’t see it working. I have a bad case of Dawn Phenomenon and *have* to eat breakfast or my blood glucose keeps rising. If I don’t eat, by mid-afternoon my bg will be over 200!
    I’ve never understood how this works – since I’ve been low-carbing for over a decade, one would think my glycogen stores would be pretty darned empty. And gluceoneogenesis doesn’t seem to be *that* fast. So I’m not sure how this happens – but it does. My body seems to think I’m freaking starving to death and in desperate need of glucose and goes into overdrive to produce it.
    Until I eat, exercise doesn’t lower my bg either. It actually *raises* it. I can exercise just fine after breakfast, or in the afternoon or evening, and it lowers me as expected, but if I try to do a quick jog or weight session or even a walk early morning before breakfast, my blood glucose goes nuts.
    I’ve been on insulin for about a year and find my blood glucose keeps rising in the morning until I eat even *with* basal insulin. I can take a shot of bolus to knock it down, but… well, frankly the notion of taking shots and NOT eating is just annoying. I try to minimize the amount of insulin I take overall as I think high serum insulin is just *slightly* less damaging than high blood glucose. So I don’t really want to take a bolus and not eat, seems a waste of insulin.
    The secondary reason is being on meds that have to be taken twice a day and should be taken with food. I don’t think 5 and 9 PM would be good timing, seems to me they work best if taken at breakfast and dinner so as to be spread out. I prefer to take them at least 10 hours apart.
    Most I’ve done is a semi-fast. I can mix up a protein powder shake, drink half of it for breakfast and half at dinner. It’s not for calorie-reduction or any other perceived health benefit, it’s just that sometimes I get sick of planning meals, of calculating the grams of carb and protein in order to figure my bolus, of the whole *problem* of eating and maintaining bg. The semi-fast gives me a bit of a vacation from all that nonsense – as much of a vacation as I can take without harming my health.
    If you don’t have it, you should get a copy of Dr. Bernstein’s book. It will explain much of what is going on in your situation.

  58. I belong to a forum that primarily uses some form of ketogenic diet to control epileptic seizures. Of of the administrators has a son who is very prone to seizures. He has to be very careful as to regulate the meal frequencies/fat/calories/proteins etc. As a matter of fact if he gets a hair too much protein he will have a seizure. Perhaps he too has Dawn Phenomenon.
    I don’t always “skip” breakfast, but I always have a big gap between meals. For example on Saturdays I will eat breakfast because I teach from 11:00-5:00 pm straight. I could take a quick break if I want it but instead I practice my flute during this time. Then I eat at supper time which is usually around 6:00 PM. This works quite well also. So I think it is possible to break up a fast and get the same benefits. It is less stressful, methinks.

  59. For about a 2 weeks i have only been eating 2 meals a day lunch and dinner. I eat nothing from about 7pm till noon the next day. Weight is pouring off me and i feel really good. I eat on the low GI of things. Maybe on to something here.

  60. Dr. Eades, I just want to let you know that I continue to IF. The weight continues to float slowly away. I decided to get a tattoo if I lose 10 lbs this year. My daughter told me that I should try in lose ten lbs by the time she visits in August. I have around 6 lbs to lose in order for me to reach that goal. If I should succeed then I will have an orchid on my lower back by August. We shall see.
    Good luck. I hope you get the orchid.

  61. I came to this blog because of an interest in calorie restriction, but became fascinated by the IF concept because I practice it daily for one month a year, and so do almost all of the healthy adults I know, and about 25% of the adult population of the world. We take nothing by mouth from first light to sunset during every day of Ramadan, because we are Muslim. The typical Muslim who fasts this way loses about 2 pounds during this month every year, and, of course, this contributes to lifelong health. However, many other Muslims overcompensate by eating huge, heavy, fat-laden meals at night. Still, the intermittent calorie restriction does seem to have generally positive effects on both physical and emotional health.
    I posted on this subject last year. If you haven’t seen it, you might find it interesting. Glad to have you aboard.

  62. Hi, I’m starting IF with LC. There was a post about adding coconut oil to coffee. Is this
    allowable? Would this stimulate digestion?? This would IFing so much easier for me. I’m a
    12hour nightshift worker and 59yo and it has been so hard for me to lose weight.
    I don’t remember a post about adding coconut oil to coffee. Maybe it was in one of the comments. It sounds dreadful. I don’t suppose it would hurt as long as you don’t overdo it. Coffee is allowed on the fasting days because coffee contains no calories – if you add coconut oil, you’re adding about 35 calories per teaspoon.

  63. I just want to issue another report on my IF experience. Dr Mike, I have been sticking to this for 1 1/2 years. Slowly but surely I am experiencing weightloss without any noticeable spikes in insulin. My health has not suffered as a result and my low carb/ketogenic diet is to blame. IF is actually a ketogenic diet right? I began including IF with my low carb diet April of 2007. I continue doing this and I went from 166 lbs to 140 lbs. I see that comments will be closed on July 24th 2009 and I plan on updating you by then. My weight is easing off as I grow more in charge over my appetite. In general I eat 2 times a day with a 20 to 23 hour fasting period. Today, I ate once because I had eaten poorly Sunday and Monday. I buffed up my dinner menu for today because I ate only once.BTW, I baked a pork roast in some collard greens with bacon. As expected, I had a BM within an hour after eating. I have a glucose monitor and one day I will learn to use it. I would like to know how stable my glucose is on IF. The most surprising part of IF is the ability to go for so many hours wihtout an insulin spike. I don’t get weak which proves to me the importance of low carb eating. I had gone without food back in the day, and I would become shaky, jittery, irritable and headachy. That does not happen when you are eating rich amounts of fats and protein.
    I had to share that,
    Thanks for the interesting IF dietary history.

  64. I just read the previous post and I want to add that I do add coconut oil to my coffee, I also add mct in my water when I take my supplements. One thing I do is listen to my body and I don’t go by the rules of IF. I do this as if I were a cave woman. She IFed out of necessity. If she had easy access to coconut oil and she found that it helped her to make through the day until her mate, Crusher, brought home the bacon. She didn’t go by rules nor did she have a book as a reference. She did intermittent fasting out of necessity. I find that coconut oil and/or MCT keeps my stomach from growling . So, I usually add CO to my morning coffee. It is actually pretty good.

  65. [Also posted in repsonse to an older IF article]
    44 year-old male here. My experience – all positive – so far.
    I started intemittent fasting in August 2005, so at time of typing, I’ve been doing it for
    The regime is simple – eat one day, NOTHING the next, so including sleeping hours, it works out at 14/34 in terms of hours eating/hours fasting for every 48 hour period. The only things I consume during fasting days are water, tea and coffee (no sugar!) with a tiny bit of milk.
    I also excercise, burning off 1000 calories in 55 minutes on a lateral trainer, on fasting or eating days, there’s no effect on my ability to do so. At the moment, I’ve slipped to just once a week, but I also briskly walk a minimum of twenty miles each week.
    Weight: Lost 30 lbs during the first year, nothing after, but if I up the exercise, I do lose more. My weight is therefore remarkably stable for someone who has in the past fluctuated quite a bit when not exercising.
    Pulse: Has been measured at 47 when I was particularly relaxed, usually averages 60.
    Blood Pressure: 120/70 – not that impressive, one study showed an average for this diet of 100/60.
    Blood Sugar: Low.
    Food: You really appreciate it more. Eating daily, you just take it for granted.
    Time: An extra two to three hours spare time on fasting days.
    Illness: NONE. Colds – NONE. Flues – NONE. Coughs – NONE.
    The last seems to be the most remarkable benefit of this regime. And you’ll only be hungry for the first seven or eight months. After that, it’s a BREEZE!

  66. Found Dec 4 post by S Reed interesting above. Would also like him to write about food selection. When I dropped wheat recently, my blood glucose dropped from 95 or 96 down to 71.

  67. I do really like S Reed’s post,
    We are discussing IF on Jimmy Moore’s blog. There are some who are speculating doing this. Like S, I lost nearly 20 lbs my first IF year. Also, I can lose more weight when combined with exercise. I have not been sick at all. I plan to have bloodwork done this December while on winter break.Although I do not fast in the same extreme as S, I do have very similar results.

  68. I started IF a couple of weeks ago. I’ve tried fasting before but with no luck. then I read everything I could find here and on pubmed which supported the idea that I wasn’t going to die if I went without food for a few hours. 🙂 psychology is an important factor in IF, in my opinion.
    I’m up to 16-19 hour fasts so I’m not at full 24 hour fasts. Not sure if i’ll ever get there. my goal is to eat dinner each evening and then nothing until the next evening.
    My most important lesson learned is to be very careful of caffiene intake even if I’m only drinking green tea. My third fast day, I drank several cups more of green tea than my usual and had not only a roaring in my head but a very sleepless night.
    Thank you for blogging about IF, I’ve found these articles and everything else on your website very informative and helpful.
    I’m glad you’ve enjoyed the site.

  69. Is IF still worth it?
    Basically, I wanted to know what is the latest research supporting IF as a health practice (comparable to CR) and whether it is still a worthwhile effort to incorporate it into my lifestyle. After all, is this hunger every other day making significant enough difference in the quality of my health (I am not trying to loose any weight)?
    Also, does the research really support IF being healthy for women? The research cited in Part II of Dr. Eades’ article indicated that it increased insulin resistance for women.
    Appreciate your comments?
    I plan another post on IF soon. I’ll address these concerns then.

  70. Here is my personal research on fasting.
    Male, aged 35, 11.5 stone (after 2 years on a low carb, less that 20-30g carbs a day), works in city.
    I tried the intermittent fasting after reading a few blogs and found it tough. So I missed lunch only…and would think about “lunch” all day. Then, I fortuitously..missed breakfast one day after a few weeks of missing lunch and noticed I never thought about lunch.
    Since, now 8 weeks of one meal per day around 7pm, I am actually quite amazed by the results. More so in fact that the low carb diet. I never feel sleepy, I can withstand the long travel so much better, and rarely get moody etc. I am quite amazed as I said. But it takes TIME, the results got a lot better after 4 weeks.
    However, to sustain myself I have had to eat a lot of saturated fats. Maybe 200-300g of cheese such as brie or jarlsberg. 200g nuts. A lot. This is on top of a protein based meal. I find if I dont eat this much fat I either feel cold or hungry the next day.
    Anyway, I can say that I never really want to get off this diet now.
    Glad to hear that you’ve done so well. Different people seem to adapt the IF to a way that fits them well. It’s interesting to me to read the different schedules that different people have settled on. Thanks for posting.

  71. I have been commenting off and on regarding my progress on IF. I continue to be happy and grounded on a low carb based IF. I feel in complete control of my appetite. I make up the rules for the way I do LC/IF. Usually, I eat within a 4 hour window where I eat 2 meals in general. Snacking is very rare, but I allow a snack if I want one. I do not believe that gorging or overeating on this diet should be a consideration. I say this because on some days I may eat like a “pig” other times I eat like a butterfly. I find that eating this way is more balanced. I am not only a low carb eater, I am a concientious eater.I continue to make healthier food choices. PLUS, if I decide that I want an occasional slice of pie or chocolate doughnut I can eat those without falling into a carbohydrate abyss. My husband is in the hospital this week. His absence makes it easier to eat one meal a day and I am taking advantage of that this week. I work in a school district whose spring break is this week, so I should be fine increasing my fast this way. What I like about IF is it permits me to decide when to fast and how long to fast. I find that no fast pattern is written in stone and can be changed from time to time. No desire to go more than 24 hours without a meal, I feel no physical insulin issues. As usual my weight fluctuates but it is now fluctuating in the low 140’s. Interesting to note is that my waist is smaller now at this weight than it was at this weight 4 years ago.I friend of mine, who is a nurse, guessed my weight to be 135 lbs. I told her not to be nice when guessing my weight. I told her to tell me exactly how much she thought that I weighed. I insisted that she guessed my weight because she kept commenting that I was getting too skinny. When I told her that I weighed 144 lbs that morning, her jaw dropped. She told me that she actually thought that I weighed 130 lbs.

  72. Despite the naysayers and reservations, it seems that a simple approach of fasting for 24 hours once per week (without modifying or increasing food intake on other days), would simply reduce your total calorie intake by 14%, about half of that used in CR diets, and is very likely to have nothing but positive benefits. (One of the additional benefits I haven’t seen mentioned here is healing time for someone with GERD.)
    I’m not saying one will lose a lot of weight, or have a big reduction in BG, etc. — just that whatever changes do occur are likely to be beneficial. Perhaps you guys are making this more complex than it is.

  73. I take out the complication of calories. I figure that my body is running normally, so I must be getting enough calories. I also do not think of fasting as CR since clories should be considered as a percentage of total food intake, not a number. Percentage-wise, I consume more calories per meal than I did before doing IF. Ketogenically speaking, the higher the ketones, the healthier the body ( as long as it isn’t T1 diabetes ). Therefore I consume a lot of fat calories. How many calories would that be? I have no idea. I think that it is more important to be ketogenic for optimal results and optimal health.

  74. In the Mattson study mentioned in Part 2 of the post, I noticed that the subjects were only followed for 8 weeks (two different 8 week periods). I’ve also noticed people who have posted here and on other boards who said it took a few months to several months to adjust. Could it be that 8 weeks is not enough time to fairly judge the effects? This is not to mention that it only deals with a daily eating window rather than a 24/24 schedule.
    I agree. I’ve been all over the place with this IF regimen. The more recent work I’ve seen has overcome my earlier hesitance about IFing.

  75. one last update before the comment section closes:
    started window eating in jan 2009. lost 6pant sizes in about 4months w/increased workouts,moderate carbs of 100g or so a day.
    stalled out for two months. eliminated grains, lowered carbs to 20-40 a day.
    im now dropping inches like i did in the initial months of IFing. if IFing doenst work, try low carb IFing. its working amazingly well for me.
    also, instead of only window eating each day, ive mixed things up with a few normal eating days (except for morning breakfast, ill never do that again) in my case, its helped to fast more intermittently, as stated above. depends on the person i suppose.
    thanks to dr.eades for education and info sharing and all the great comments. its going to make the last half of 09 as good as the first half!

  76. Tom N., In reply to your comment, it did take time to adjust to IFing. Your body takes a very
    long time to adjust to anything new and 8 weeks is not enough time to determine success with IF.

  77. Hey Dr. Eades,
    We love your site and often reference it on our blog ( I just came across your IF stuff. My girlfriend and I kept a blog of our first IF experiences from about the same time this article came out. It’s at
    We both really liked IF. We saw increased strength, energy, time, workout performance, and decreased body fat. We were super lean when we started, and got even leaner.
    We IF occasionally now, but not as regularly as we used to. We don’t usually plan the fasts anymore, they just happen. I actually prefer to go into workouts fasted (a 14-15 hour fast is about perfect). I feel hungry and ready to tackle the workout.
    Since that last IF blog update, we have continued to improve our diet. I have now gotten rid of all gut irritation and feel better going into workouts with a little food in my stomach. I still prefer to be fasted, though.

  78. Thanks for this.
    I agree, fasting can take a lot of time to adapt. However, from my experience and from the experience of people around me fasting is never as hard a transition as most people feel. To be honest I was IF’s biggest critic after spending 5 years eating 6 meals a day. Rest assured, after taking the leap into fasting I haven’t gone back to that old routine.
    I have wrote about some of my experiences, especially my review of Eat Stop Eat at

  79. IF works fine for me, but I must admit it won’t work for everybody. Some people just thought that I’m crazy and that my eating habit is really unhealthy. People without fasting expereince may think that fasting is impossible without realising that it is actually possible and with lots of health benefits. I personally enjoy weight loss, better energy level, more focus at work, better skin, better digestion…

  80. IF is my new LC! LC works, but IF works better!! (For the driven winner kind of person, combine the 2 and it’s BAM! POW! Awesome!) IF-ing alone, though, I can eat cookies and still lose weight!!! I just stop eating at 4 pm about 3 days a week and start eating again the next a.m. (I try to wait til late morning) and I lose weight like crazy. If I LC inbetween I lose even more, but if it’s a splurge sort of day with going out to breakfast and a party in the afternoon, I can eat pancakes and cake, and I still lose…it’s a winner!! LC taught me how to make good choices and I will always follow that but I like not having to stress over some bread esp. after 3 years of being so careful. It’s refreshing to just eat and not count and not worry, and then just STOP eating. I feel like a teenager again being sort of carefree! So, IMHO? — SO EASY– it doesn’t even seem fair! And that empty feeling is similair to the feeling of strict LC… it feels the same except I lose more doing it and I get to eat whatever I want! Love it! Dr. Mike, you should get on FB…that’s where loads of normal middle-aged people are…like my mother! I think it’s only cool savvy types who are on Twitter.

  81. I follow IF using the 24 hour fast method, what i found was startling. First of all, after the fast like you said, I was unable to double my caloric intake. Then I was able to control my hunger better, my appetite didn’t go out of whack. I dont binge on my refeeding days (which is so different from the usual caloric restriction diet)…… I get fruity breath and a sense of weakness at the beginning, now it’s kinda unnoticable. I can go on fasts for a full 40 hours now, it’s not such a huge deal.
    I’m not sure about the loss of metabolism, but according to eat stop eat, it’s not significant relative to the amount of calories you are cutting. If you fast for 2x a week , that’s like roughly 4000 cals out of 28000 cals, roughly 14 % ( and let’s discount it to 10 % reduced caloric intake). The loss of metabolism supposedly kicks in after 72 hours of fasting. That’s why refeeding with sufficient cals is essential and hard to achieve.

  82. So I’ve been doing an LCHF diet for over 4 years now and decided I would check my ketone and BG levels after a 24 hour fast (go from dinner one day to dinner the next) and when I got home from work my fasting ketone levels were negligible, my BG was high enough it set the alarm off on the meter and it told me to check my ketones! Anyone else ever have that happen? I felt normal as it’s not unusual for me to go over 12 hours without eating. Only thing I can think of is my sedentary job which requires me to sit and not move for long periods of time all day

Leave a Reply

Your email address will not be published. Required fields are marked *