Anyone who is a regular reader of this blog will have noticed that the last post on intermittent fasting generated an enormous number of comments, just about all of which I tried to answer. Most of these comments were questions about intermittent fasting or people giving their dietary histories or people informing us that they were starting an intermittent fast. Other comments asked for answers to specific medical questions while others wanted to know if MD and I had abandoned the low-carb diet in favor of intermittent fasting. I figured that this would be a good time to set the record straight.
MD and I feel strongly that we as a species have a genome that was molded by the forces of natural selection over the past few million years to operate optimally on the food that was at hand during those few million years. What was available? Mainly fairly high-protein, high-fat fare. There weren’t a lot of carbohydrates readily available until the advent of agriculture a few thousand years ago. For the time that we developed our ancestors ate meat, fish, insects, clams, reptiles and pretty much anything live they could get their hands on. This primarily protein and fat diet was supplemented with whatever fruits, nuts, berries, roots, shoots and tubers were in season. Work done by Loren Cordain shows that, based on the Ethnographic Atlas, modern day hunter gatherers get about 65 percent of their calories from animals and the other 35 percent from plants. Most researchers believe that Paleolithic man got more than that from animals because during Paleolithic times many more large animals roamed the earth than do today. In fact, Paleolithic man hunted many of these large animals to extinction.
It is pretty safe to say that the macronutrients that set our genome were fat and protein. Many unenlightened people seem to believe that early man lived in land of carbohydrate abundance, and, consequently, thrived on a high-carbohydrate diet. It can easily be seen that this wasn’t the case simply by calculating how much food would have to be consumed to get enough calories from the available plant sources.
Taking 3000 kcal as being the average (it’s probably on the low side) daily energy intake of our Paleolithic ancestors and looking at how much plant food would be required to obtain those kcal is an eye-opening experience. I ran just a few foods through the USDA nutritional calculator and found that it would take 48 cups of blackberries–that’s 3 gallons of blackberries–to provide 3000 kcal. I don’t know how many readers have ever picked blackberries, but I have, and I can tell you that picking 3 gallons takes a lot of time. And, much though I love blackberries, I couldn’t come anywhere near eating 3 gallons of them in a day. How about blueberries? 36 cups; over 2 gallons. Spinach? 103 cups. Celery? 111 stalks. Apples? 42.
It was only after the advent of agriculture that calorically dense carbohydrate foods came into existence and became the common fare for man. Until then, our ancestors, if they were to subsist on plant foods only, would have had a pretty rough time of it getting enough without eating all the time. Which is exactly what the mountain gorillas do. Although mountain gorillas have the same carnivore GI tract that we do, early in their evolution (probably lead by the gorilla version of Dean Ornish) they opted for vegetarianism. These animals eat constantly to get enough plant food to meet their energy needs. They take food to bed with them so it will be available when they first awaken. They roam through the jungle throughout the day eating non-stop except for brief rest periods.
Given the above facts, it’s pretty clear that early man ate a fair amount of meat. After all, it takes only a couple of 16 ounce fatty steaks to provide 3000 kcal, which is a whole lot easier to down than 3 gallons of blackberries. It would then stand to reason that as a species we would perform better on a meat, or at the very least, a higher protein, lower carb diet since that’s what we had to eat for a few million years. In one of my favorite quotes, Dr. Blake F. Donaldson, a crusty old physician from New York who wrote a book called Strong Medicine, says:

During the millions of years that our ancestors lived by hunting, every weakling who could not maintain perfect health on fresh fat meat and water was bred out.

When we saw patients in our clinic for obesity and the other so-called diseases of civilization, MD and I successfully treated them with diets that approximated what we–based on the anthropological evidence–believed early man ate. We basically gave them the food they were designed by nature to eat. Obviously we couldn’t have them eating fresh mastodon steaks or cave bear fillets, so we had them eat the modern day equivalent (or as equivalent as it could get in the modern day) that could be found at the grocery store or in restaurants. We had to develop a diet that was palatable, not overly difficult to obtain and prepare, and that would allow them to live their regular lives and go about their business. After refining and tweaking, the diet we came up with is what we described in the book Protein Power. We diddled with it a little more and added a few supplements and made some more lifestyle recommendation such as getting more sunshine and getting rid of excess iron that went along with our Paleolithic origins and published the Protein Power LifePlan.
Since that time we’ve continued to think about the optimal diet and experiment with different permutations of the Paleolithic diet. We still believe that a low-carbohydrate, higher-protein, higher-diet is the optimal one for humans. In thinking about how to make a low-carb diet better, it dawned on us that there is another factor besides the actual food eaten in any particular diet: the timing of the eating. We began to think about how often Paleolithic man ate. We looked at data from modern day hunters and found that most of them didn’t eat all that often, and that when they did eat, they gorged.
Once we decided that meal timing was probably important in the development of our genome just as was the kinds of foods consumed, we started looking for evidence in the medical literature. There we came upon the studies on intermittent fasting (IF).
I covered intermittent fasting at length in the previous post. I was amazed that whatever goes on during the fasting process is potent enough to overcome the health negating effects of ad lib feeding because the animals that were underwent the IF had the same health benefits as did those that were calorically restricted yet the IF animals ate the same as the (ultimately sickly) ad libitum fed animals. And the IF animals lived as long as the calorically restricted animals despite eating as much as the much less long-lived ad lib fed animals.
Clearly something powerful takes place during a fast. What is the mechanism? Who knows at this point. But it’s something that should inspire a battalion of researchers to get busy looking into.
Now, based on the IF research data, MD and I are of the opinion that a Protein Power style diet interspersed with a little fasting is probably the optimal diet. We ourselves follow this diet. We eat one meal a day sometimes, a couple of meals others, and sometimes three squares. If we’re not hungry we don’t eat. We try to fight off the culturally induced feelings of, Oh, it’s lunchtime, so I must we must be hungry: let’s eat.
We tried the IF as written up in the post because we wanted to see if there was a particular regimen we could give people wanting to try it out. We know from many years of taking care of people on diets, that dieters want rules. The more we would write our material in such a way as to give patients (and readers) a lot of lee way in how they could prepare their low-carb diets, the more calls we got from these patients asking for us just to give them a set of meal plans. We found that the IF was easiest for us with a 6 PM cutoff; that’s why I described it that way.
There is probably no magic in the 24 hours; who knows, maybe it’s 15 hours. It just isn’t known at this point. I’m firmly convinced, however, that there is an advantage to going without food for periods here and there. I’m convinced for a couple of reasons. First, all the data on IF is pretty persuasive. Second, all the Ornishes, Barnards, Grundys and the other AOE (Architects of the Obesity Epidemic) recommend that we all eat a lot of small meals throughout the day. Given the track records of these people alone, it militates that we should eat large meals separated by long periods of time.
We still fully believe in Protein Power. We haven’t abandoned it in favor of IF. We have added IF to our own lives from time to time, especially if we go off the Protein Power wagon. But, we also IF using strict Protein Power, too, In short, IF is just an adjunct to the Protein Power diet that makes it work better by making it even more like the Paleolithic diet we cut our collective teeth on.
Once again I have to reiterate that I can’t answer specific medical questions over the Internet. Unless you’re my patient (and by that I mean someone who I have examined) I can’t tell you why you’re having this reaction or that. If your ankles are swelling, I don’t know why unless I can take a medical history and examine you. If you’re exhausted on the IF or any other regimen, it could be that you need a little potassium, or it could be something else. Whatever it is, I can’t give you an answer unless I take a medical history and do an exam.
One final note:
One of the commenters on the IF post is Robb Wolf who has worked with Loren Cordain and is himself well read on the literature of IF. He sent me an interview with Dr. Thomas Seyfried on ketosis and cancer that he said I could share with my readers. (click Download file to download the PDF) In the interview Dr, Seyfried discussed IF and some of its therapeutic uses. (You can also click here to read Dr. Seyfried’s paper on ketosis and brain cancer published this year in Nutrition & Metabolism)
Robb is the Editor-in-chief of the publication Performance Menu: Journal of Nutrition and Athletic Excellence, which contains articles on IF. (Click here to take a look)


  1. Dr. Mike thanks for the clarification, especially for those members of the PP Forum who also read your blog daily we have had alot of questions to be sure.
    Like any new program, it is important for people to really investigate it, just like we all did before starting Protein Power and not go down the road with IF without thoughtful analysis or just because someone pops into the web site and talks about it.
    I appreciate so much your clarification, the reasoning and the data. We can link this right into the board now and refer people to your commentary.
    My concern from the board was that people saw it is a “quick weight loss” kind of approach or gimmick if you will rather than the reasoning behind the efforts, so again thanks.
    Hi Billie–
    Thanks for all your help with the board. I’m hoping this post reduces the confusion.

  2. Thanks for the informative post Dr. Eades. It’s a nice concise essay on why it makes so much sense to eat lowcarb. People are confused by all the agenda-driven pseudo science spewed forth by the media. As soon as one study comes out, another one appears to contradict it. Or so it appears to the uninitiated.
    However, it’s hard to argue (deluded vegans aside) about the past that shaped our species.
    So this is a good essay to give people to read.
    A suggestion, if I may be so bold. Now that you have a forum, could you not talk to your tech guy and link each of your blog entries to a new topic on your forum. This way there wouldn’t be such an onus on you to respond to each individual post, since that is not usually expected in a forum.
    Hi Angelyne–
    Thanks for the kinds words about the blog. And for the suggestion about linking to the forum. The last post on IF certainly generated enough comments that it took a ton of time to deal with them.

  3. You celery stalk number seems to be too low. According to the USDA database, a large celery stalk has 10 kcals, so it would take 300 large celery stalks to total 3000 calories. Or 500 medium (6 kcal/stalk) or 1000 small (3 kcal/stalk).
    Hi Mike–
    I must have misread the chart. Whatever the number is, it’s way more than I could eat in a day.

  4. Great post Dr. Michael. I don’t use the quote “The Real Human Diet is a Totally Carnivorous One” for nothing! My point earlier was that on a zero carb diet, or maybe even a very low carb diet, it should happen naturally, and even if it doesn’t, keeping carbs at the absolute minimum is always the best route to take.
    Personally, I think people eating as little as 20g/carbs per day can stop losing weight and stalling so there’s lots of interest in things like fasting and the “omega” plans. I think the bottom line though is that it’s always about glucose. There’s no magic bullet outside of eliminating carbs entirely.
    I look forward to reading that interview. Thanks.
    Hi Rob–
    I’ve experimented a bunch with a meat only diet and found it to be easy to follow. I may post on it once I get over my writer’s cramp from the IF post.
    Thanks for writing.

  5. rather ironically hilarious how a post on not eating produced so many queries about eating !
    Ye know Richard Veechs work ? He’s the am told.
    Hi Simon–
    Yeah, ironic indeed!
    I do know Richard Veech and his work. He and I went mano a mano once at a conference until we realized we were talking about different cells. I was talking about liver cells, Veech was talking about cardiac cells. He’s an interesting guy who is much opinionated. But, so are we all I guess.

  6. Mike, thanks for the clarification.
    Since it has been mentioned, I’d be interested to read studies where a ‘zero-carbs’ approach has been compared to a non-zero, even if is as little as 20 gr of effective carbs. As far as weight loss is concerned, I don’t see how no dietary carbohydrates at all provide ‘more’ measurable benefits than a limited amount of carbs (say 30 gr ECC/day as recommended in Protein Power). What I mean is that weight loss doesn’t follow a linear relationship with carbohydrate intake (hence the existence of true stalls). There may be a carbohydrate limit in which insulin secretion is finally stabilized, so fat synthesis, fat internalization and cholesterol synthesis (to mention a few processes only) are under control, below which there is no real metabolic difference. I suspect that ‘zero’ doesn’t bring more control than a limited amount of effective carbohydrate, such as 30 gr.
    That’s not to say that one cannot live without dietary carbohydrate at all. Indeed we can and when other foods are available we also take the best out of them. But that’s different from saying that ‘zero-carb’ is always the way to go. We didn’t evolve as omnivores for nothing and that helps us adapt to different situations of food availability. What we didn’t evolve to is to live on carbohydrate as the major component of the diet. It seems time is proving that right, given the number of metabolic disorders caused by adhering to such diet.
    Borrowing from a microbiological term, I think of us humans as ‘carbohydrate facultative’; we don’t strictly need dietary carbohydrate as an absolutely essential nutrient to support life, but if it’s available we can and will use it.
    Hi Gabe–
    Those would be interesting studies, i.e., checking for weight loss as a function of carb restriction right down to zero carbs.
    Carbohydrate facultative, what a great term. Mind if I steal it?

  7. I liked your description of the AOE so much, I’ve decided to change my username. Heh.
    I think some of the confusion lies in how you said you ate higher carb during your intermittency. I’m pretty sure I know why you think this is justified, but perhaps it would be best for you to explain in a bit more detail.
    Hi AOE–
    Glad you liked it.
    The reason MD and I did IF in the first place was to see if we could eat more carbs on the eat days and still maintain the benefits of an LC diet. It appears that we could, but the problem was, we were so used to eating LC that that’s pretty much how we did it on the eat days. We did eat more carbs at the beginning, but once the novelty wore off, it was pretty much back to LC when we ate.

  8. I find the whole IF thing very interesting.
    I did it in 2003 (the Warrior Diet version) and had great results. However, the foods were sub optimal as the author is big on whole grains and such.
    But since reading DeVany’s stuff since 2005 I started IF-ing relatively regularly, in the framework of a lowcarb diet, and your posts made me try it for real for the last 3 days.
    I really enjoy the freedom from having to prepare breakfast and lunch during the day.
    I do feel some hunger, but much less than when I did the low-fat, high carb version of IF. In fact, it is almost pleasant.
    However, I do have a question.
    Since I work long hours (sometimes 12-14 hours per shift), at the end of the day I start to feel somewhat light headed and tired since my last meal usually finishes at 10PM the night before. I figure my body will get used to it, although I would prefer to eat earlier (from 6-10 PM).
    However, I prefer to wait until I am finished working to eat. Is it a good idea?
    My schedule may look like this:
    Meal from 9PM to midnight, sleep from 1AM to 6 AM, work from 7 Am to 8 PM.
    Also, like you mentioned, I have trouble fitting my 3000-some calories at one sitting. So sometimes I fall under that mark. I sometimes do include a small 300-500 calorie lunch (cream and coconut oil with instant coffee).
    As WaltK mentioned, I also get a surge of energy at the end of the day, around sundown. Makes it perfect to workout then, High-intensity/Slow Burn style.
    I included a little story that could be interesting, from Steffanson’s autobiography (Discovery) relating the dietary habits of Lord Strathcona, Canada’s Canada’s High Commissioner to England in the late 19th century. He lived to 94 and followed a high-fat, IF regimen:
    “My first contacts with him were merely casual occasions for him to use his position as Canada’s High Commissioner to expedite the work of the Canadian Arctic Expedition. It was not long, how­ever, before there grew up between us the bond of a common interest — an interest in dietary matters. I told him what I had learned from the Eskimos, and he told me that years ago in Canada he had begun a regimen all his own by skipping lunch and ultimately breakfast too. Then he had begun to wonder why, since he liked some things better than others, he should bother to eat something different on Tuesday when he had liked what he had eaten on Monday better. This led to his questioning what he really did like and, when he got the answer, eating nothing else — eggs, milk, and butter. Although this combination would not have made up my favorite meal, much as I favor butter, the point was that Strathcona and I were in agree­ment on the feeling that the longer a man ate one complete food exclusively, the more likely he was to relish it.
    “I had many opportunities to observe the High Commissioner while I was in London, for he frequently invited me to dinner at his home in Grosvenor Square, saying that So-and-So would be present and he thought I would like to meet him. Strathcona, a broad-shouldered man taller than six feet, would be seated at one end of the long table, Lady Strathcona at the other. As course after course was served to the rest of us, he would converse, drinking a sip or two of each wine as it was poured. Sometime during the mid­dle of the dinner, his tray was brought: several medium-soft boiled eggs broken into a large bowl, with plenty of butter and with extra butter in a side dish, and, I believe, a quart of whole milk, or per­haps half-and-half. My impression is that they also brought him toast, but that he barely nibbled it, using it a bit as if it were a napkin.”
    Hi tbonemitch–
    Thanks for the Stefansson story; I remember reading it when I read Discovery years ago.
    I don’t think it’s a problem following the schedule you’re following. You might try drinking some bouillon or some other salty drink late in the day to give yourself some sodium. A potassium supplement would probably help, too. One of the reasons people tend to get lightheaded on fasting type regimens or even strict low-carb regimens is that they get a little dehydrated and drop their blood pressure. A little sodium along with some fluids usually solves the problem. The potassium supplement is because anytime anyone is sodium depleted he (or she) is usually potassium depleted as well.
    Let me know how it works.

  9. Mike, be my guest, but I know you are incapable of stealing. I use it all the time when I teach. By the way, I have some research ideas that I am putting together that have to do with nutritional biochemistry. I have thought on the relationship of weight loss and carbohydrate control. Conceptually, those studies are not very difficult, except perhaps in deciding what is the best design (various groups doing specific carb levels, one group starting at one amount for X time, then reducing carbs for the same duration, then reducing, etc). The most difficult part would be the ethics… since you know ‘carbs are essential and substantial reduction would throw people into ketosis and they could die…’ [sarcasm here]. I’ll have to provide extensive references to support the safety of the subjects. I have a chance to present a research proposal in the coming weeks and I would very much like to tackle this issue. Hey, maybe that would give me a ‘platform’, if you know what I mean! Anyway, if you have any suggestions, I’d love to hear them!
    Hi Gabe–
    Sounds like a great study; do you need a co-author?

  10. Hi Mike,
    Thanks for the interesting topic. As you know it has stirred a lot of interest, and not just here. I realise and appreciate the reason that you can’t give individual medical advice, but I wonder if you would consider a general post on the topic of hypoglycemia in the context of IF, to deal with the concerns of those of us whose blood sugar may dip too low on occasion, especially so with larger than ‘normal’ gaps between meals (even after long term low carb adaptation – which would tend to eliminate reactive hypoglycemic incidents?). I am also interested in whether low blood pressure (which gives similar symptoms) could also be a possible side effect, perhaps because of electrolyte depletion?
    Hi Malcolm–
    I would put my money on an electrolyte depletion. Not eating forces the liver to produce glucose via gluconeogenesis in order to supply it to those tissues that require it. The liver usually produces glucose at a nice even rate so that levels stay pretty stable. The increased insulin sensitivity and consequent fall in insulin levels ensure that the kidneys get rid of excess fluid, often taking sodium and potassium along with it. And sometimes people experience a little mild dehydration. Any or all of these mechanisms can cause light-headed, dizzy sensations.

  11. Dr. Mike, Have a question. I have read many times the theory “THEY” put out on how many calories one is supposed to eat in a day. Some say no less than 1000 and other 800. Something about your body shutting down and starvation hormones and all that. Is their any truth to this? I am not exactly who “THEY” are but “THEY” seem to rule the world. Thanks
    Hi Tess–
    Unfortunately, ‘THEY’ are often ignorant, which ‘THEY’ indeed are in this case. Metabolic rate is pretty much set by weight and, to a lesser degree, the amount of activity. There is a small component of overall metabolic rate that is a function of the energy required to digest the food taken in, but it’s a fairly minimal percent of overall metabolism. And, as soon as you eat, there it is again.
    Hope this helps.

  12. Wonderful article! I was just hoping you could expand a little on the following comparison:
    A) Fasting all day and then eating one large (low carb) meal each evening around dinner time…
    B) Full eating days from waking until bed, separated by full fasting days….
    C) The program you folks did.
    Please keep in mind I’m after PHYSIOLOGICAL pros and cons of the above, not necessarily psychological. I myself am routinely doing example “A” and find it easy and enjoyable. However if there are physical benefits to either “B” or “C” over and above those of “A” then this is something I’d like to consider.
    Thank you!
    Hi Jennifer–
    I don’t know if there are physiological differences between the methods you listed. I think that when all the data is in what will be found to be important is that there is a fairly lengthy period where no eating occurs. I have no idea what will be found to be the optimal length of this period. Until such research is completed, I would do whatever works best for me.

  13. Mike, are you for real? It’d be great if we collaborate! I’m narrowing the ideas down to two and I’ll have to decide for one, which is the most difficult part. One is more fundamental (i.e. molecular aspects), on the increase in energy expenditure that occurs after increasing dietary protein while keeping fat intake unchanged. Some studies have shown that such increase seems to also increase the expression of certain homologues of uncoupling proteins (that also happens with fat intake but is more specific for UCP1). The problem is that the studies call ‘normal’ fat a mix that has only 5% (go figure!), and ‘high’ fat a mix that has only 17%. I haven’t seen many reports of dietary protein directly increasing the expression of UCPs and that alone is very interesting! Related to that is also the way the mTOR pathway works when fed with certain amino acids (leucine in particular). I suspect there is a lot of energy required there and it has to come from somewhere… who knows, there may be a connection between that and increased thermogenesis, that is worth tackling too. The other idea is, as mentioned above, a rigorously designed study in humans with good counseling, and food questionnaires that are more reliable than the Food Frequency Questionnaire (such as the 24-hr dietary recall), estimation of protein intake based on size and level of physical activity, etc. Lots of thoughts to sort out still but if you’re interested, I’d be glad to keep you posted!
    Hi Gabe–
    I’m interested. Keep me in the loop for sure.

  14. Mike it’s great to see lots of people trying IF. I’m now following your regimen and find it very easy.
    Just a small thing about how comments are posted in your blog. I find it difficult to follow who is posting because it seems illogical to me to have the commenter’s details under a solid line after their comment. Perhaps it might be easier to follow if the solid line was first, then the commenter detail then the comment. This way all the information from a particular commenter would be in one block. Sounds pedantic when I read it back, but I think it would help.
    Hi John–
    I think the way the comments are presented is the way this software does it. But, I’m getting ready to change to a different blogging software program, so we’ll see how that works.

  15. Well I survived my first fasting day!!!
    Actually it was fairly easy. I actually only fasted for 22 hrs (because I decided to do this late last night). I drank a lot of water, some hot tea (with milk) and a sf soda. To break the fast I had a huge taco salad (beef, home made) and then later a piece of home-made cobbler (raspberries and blueberries).
    I don’t think I’m going to do the fasting every other day, maybe once every 2 or 3 days….but we’ll see.
    Hi Cindy–
    Thanks for the update; keep us all posted.

  16. Hi,
    I am an admin in a active low carb forum in Finland. I would love to translate your articles about Intermittent Fasting and see if people are interested in trying it for a month or two. Is it okay to translate the articles?
    I’d report the results to you.
    Hi Hoover.
    Be my guest. Translate away. Just keep me posted on the response.

  17. Are not most of the wild animals today quite lean e.g. rabbit, deer etc.
    If this was the case in prehistoric days, it would mean humans are suited to low carb, high protein, medium to low fat. I don’t know enough about climate etc. but I suppose if it was cold, the animals may have been quite fatty.
    Suggestions for other areas of study (sorry if you have already covered them):
    a) when to eat in relation to exercise
    b) what type of exercise is best
    c) intermittent high carb meals (every couple of days, weekly, fortnightly)
    Hi Dan–
    Many wild animals alive today–at least the ones typically hunted for their meat–are fairly lean. It has been shown that the larger an animal is, the greater the fat content. In our prehistoric days, early man hunted large animals. In fact, the cave bear, the ancient bison, the mastodon, the mammoth, and a host of others were all hunted to extinction. Another thing early man did that we don’t do today is to eat the entire carcass. Today’s man eats the muscle tissue and pretty much nothing else. In days of your it was all consumed except for the bones, and even those were split to get to the fatty marrow. The entire carcass has a much higher fat content than the muscle alone.
    A good description of the way early man ate an animal is in the first couple of paragraphs of the chapter on fat in the Protein Power LifePlan.
    I’ll cover your other questions in posts to come.

  18. Dr Mike
    I’m still having a problem with swelling of the lower extremities late in the day, but this morning when I bent down to check my legs, I bent all the way down — it seems my tummy is disappearing! I imagine that my body is simply doing certain things in its own time.
    I’m on my 5th 48 hrs, and everything seems to be going okay. I don’t feel much hunger, probably because I was already doing nearly zero carb, but I didn’t realize how boring it is when I’m not preparing to eat! There’s a lot of time now for something else.
    Hi LC–
    I have this running jibe with MD (actually the whole family does; the kids love it) that I can always tell where she is in her eat cycle. She’s either talking about the last meal or planning the next one. When we went on the fast, it made the part in the middle a lot longer than normal. She actually had a time period when she wasn’t thinking about the last on and hadn’t started to think about the next one. Looks like you’re in the same boat.
    I’m glad the tummy is shrinking.

  19. Dr. Guzman-
    You might look to the established ketogenic protocols used by Stanford University in its epilepsy treatment program. You have a deep data pool of people using a KD in a therapeutic fashion.
    Just a thought.
    Hi Robb–
    Thanks for the recommendation.

  20. The internet is rife with posters claiming they are eating less but not losing weight. You seem to be saying that metabolic rate is not tied to energy intake.
    Are they all liars?
    In your clinical experience, did you NEVER come across somebody who should have been eating a small enough amount of calories to lose weight but who wasn’t?
    Hi AOE–
    Total metabolic rate is the sum of the RMR (resting metabolic rate), the physical activity level (PAL) and the thermic effect of the food eaten (TEF). The RMR, which is the largest contributor to total metabolic rate by far, is a function of weight. Many studies have shown this. The PAL, of course, is dependent upon the level of activity, and the TEF depends upon the kinds of food eaten, with protein providing the greatest TEF, fat, the least.
    Having said all that, there are a few other factors at work that are too complex to get into here, but that I plan on posting on later.
    I don’t think that everyone who claims to eat very little and not lose weight is a liar. But…
    Let me say this, we had all of our patients fill out detailed food diaries. Whenever one came in and complained of not losing weight despite sticking exactly to the plan, we would go over the food diaries in detail. Usually we could see the problem right off the bat; occasionally, however, a patient would bring in a food diary that showed he (or she) had eaten practically nothing in the previous week and what had been eaten was exactly what we would have had this patient eat. When this happened, I would make the patient a bet. I would say, you come stay under my complete supervision for one week, and I will feed you exactly what you have written down in your food diary, and if you don’t lose weight, I’ll give you $10,000. If you do lose weight, however, you give me $10,000. I never had anyone take me up on it.
    People often fool themselves in terms of the amount of food they really eat.
    If you want to see this in action, go to a serve-yourself, all-you-can-eat buffet kind of place and watch what people eat and what the people doing the eating look like. You will see obese people piling plates high with all kinds of food and going back multiple times. I guarantee you that a number of these same people are going to their doctors and saying: I just don’t understand it, I almost don’t eat anything at all and still can’t lose weight.
    How do I know this? I’ve spotted my own patients at these buffets.

  21. What effect would Intermittent Fasting have upon one’s weight lifting performance, especially since one of the key trends now seems to be post-workout nutrition? Also, in regards to eating 5-6 small meals per day, in terms of fat loss, what difference does it really make whether you eat 3-4 meals or 5-6, as long as you make good food choices? I find that it is very hard to fit in a lot of smaller meals, without having to be constantly planning and checking the clock to see if it is time to eat.
    Hi Jacob–
    I’m going to post on these very issues soon. Stay tuned.

  22. More energy, lower resting pulse & BP, not really more hungry on IF days than eat days, and my kcals are down about 20-30% when I do eat, so WAY less food overall.
    Gonna keep at it, but have a ?
    Should I be trying to pack in enough protein on the eat days to ‘cover’ the fast days? PPLP recommends I get 102 grams/ day – so 204 if I fast every other day?
    Hi Nean–
    No, I would just eat whatever is comfortable and filling on the eat days and let nature take her course. The body is capable of sparing the lean body mass from depredation as long as you’re getting a decent amount of protein on the eat days.

  23. I am going ahead with the I.F. and not doing too badly. My exercise has dropped off because I find myself without the energy to get at it. My BP unfortunately has not dropped and my allergies just keep on, but two weeks is just up so I am keeping on. I intend to keep it up to see what happens until I leave on vacation next Tuesday. My schedule works well with the trip because I am not scheduled to eat on Tues. until evening and Tuesday is when I will be flying, and they never serve anything I will eat anyway, so when I land and am met I will be able to go to dinner with a clear conscience. But that will be the end of I.F. for me, at least until I get home again and have a chance to review the benefits (if any).
    It has been an interesting experiment, I just wish I had been able to see my BP go down as I am allergic to so many of the BP medicines my Dr. prefers and my BP is not well controlled in spite of low carbing. I have however finally lost a pound and a half as of this morning and that pleases me.
    Thanks for the blog and for all the help.
    Hi Ruth–
    Congrats for hanging in there. I’m glad to see that you’ve dropped a pound and a half. Hope it’s more before you give it up.
    Although the majority of cases of high blood pressure respond to a low-carb diet, not all do. In my experience about 15% or so of patients with HBP still have to remain on meds despite losing weight and doing well on a low-carb diet.
    I hope that as you continue on maybe your blood pressure will fall into the normal range. I’ll keep my fingers crossed.
    Have a good trip.

  24. Add me to the list of happy IFers. I love the every other day off feature, sometimes do a little more than 24 hours fasting. I actually feel more energized on the fasting days, not less as many have reported.
    Please continue to post on this subject.
    Hi Charles–
    Thanks for the info on your experience.  I’m happy that it’s working so well for you.
    I plan more posts on IF in the near future.

  25. Dr. Mike,
    Thanks so much for these two articles on IF. I’ve spent a good part of the last couple of days reading them and through ALL of the comments. I must say you are extremely generous with your time for answering everyone’s post, even though many commenters on the original article didn’t seem to feel they could spend the time to simply read your answers to previous questions which already answered theirs!
    Anyway, I’ve decided to try IF, and this is my first day. So far so good. I am doing the one meal (dinner) per day variant. I only started getting hungry in the afternoon and have a question relating to this. I’ve been drinking water throughout the afternoon and have noticed that when I drink some, I will feel like I’m satiating the hunger, as if the water is fooling my stomach into thinking it’s getting food. Then a minute or two or three later, the hunger pangs come back. I’m wondering how to deal with this? I see two possibilities – either drink water constantly in order to head off the new hunger pangs, or simply stop drinking it once the hunger pangs come – I’m assuming they will subside after a few minutes as that has been my experience in the past.
    Also, I seem to recall someone mentioning the possibility that drinking a lot of water , and thus “fooling” your stomach into thinking you were eating, might actually cause an insulin response. Was this just my imagination making this up?
    Finally, I still getting used to the idea that metabolism is based mostly on your weight. For so many years I’ve heard the same thing about “starvation mode” referring to metabolism slowing when not eating enough calories. It made sense in a similar way that some of the anthropological theories you espouse around diet do. IE, when our ancestors were experiencing a dry period and not getting much food, the “starvation mode” kicked in as defense mechanism, which lowered their metabolism so they wouldn’t burn as many calories, and thus not require as many. But something always bothered me about it in that I heard it all the time but never, ever heard about any studies that even touched on the issue. I’m wondering whether metabolic rate can even be quantified in a study, but your discussion of it reminds me of so many other myths that you debunked in Protein Power and Protein Power Lifeplan. I wonder if you’ve done any research regarding when the initial idea of “starvation mode” came about and then how it grew from a suggestion into a “known fact”?
    Regarding my own experience, I had great success when starting Protein Power back in 2000, and lost 25 lbs over a year. Not super fast, but I felt great and became an active participant on your board and eventually moderator. But soon after losing the weight, I met my now wife, and there was suddenly little time for exercise and a lot more reasons to eat out! I’ve stuck with the spirit of Protein Power, but I’m also a small guy who tends to eat large potions quickly, and so the weight came back. I’ve been back on the plan for the last 4 weeks very strictly and have re-lost some weight. I’m hoping that IF will not impede the weight loss, but I still plan to log everything so I’m sure not to go too crazy, and I also plan to basically stick to the same carb limits, albeit in just one meal of 40g vs. the 3+snacks adding up to the same. I think this will give me some added flexibility in adding back some higher-carb (but nutritious) choices like yams, squashes, and perhaps even rice (I don’t want to experiment with other grains due to the concerns you raised in Protein Power Lifeplan), and more berries than I normally would eat.
    Anyway, thanks again for this blog, your books, and continually giving me lots of fascinating ideas to think about!
    Hi Levi–
    I’m glad to hear that you got hitched to a good woman, but sad to hear that you regained your lost weight.
    I hope the intermittent fast works for you.
    As to your questions…
    Hunger is a complex reaction with many components.  There is a chance that the slight dilution of your stomach acid brought about by drinking a bit of water could cause a temporary quelling of hunger pangs.  It’s the only thing I could think of.  I don’t really believe drinking water is going to affect insulin secretion at all, so I wouldn’t worry about that.
    The studies I have read virtually all correlate metabolic rate to body weight.  I’ll be the first to admit that I haven’t read every study published on the subject, but the ones I have read all conclude that metabolic rate is a function of body weight.  That’s not to say that there isn’t some kind of what you refer to as a ‘starvation response,’ however.  When people are well fed, they deal with excess calories in a number of fashions: they store some as fat, they burn some to metabolize the food (especially protein), and they increase their futile cycling.  What are futile cycles?  Futile cycles operate to dissipate excess energy by converting substance A into substance B, which is then converted back into substance A.  These cycles use calories that would otherwise be converted into fat.  Also, there can be leaks across the mitochondrial membrane and even uncoupling proteins that dissipate energy.  During the ‘starvation response’ all of these processes can slow down, making weight a little more difficult to lose.
    An easy way to think of it is using a car as an analogy.  Think of the engine as your calorie burning body and the gas in the tank as your stored fat.  To make the analogy even more correct let’s say there is a small leak in the gas tank that would represent all these futile cycles.  If the engine were to get bigger or smaller it would use more or less gas, which is pretty much in line with what happens in the body: bigger body, greater metabolic rate.  If you were to plug the leak in the gas tank it wouldn’t change how the engine runs, but it would certainly make you run through gas a whole lot more slowly.  Same thing with shutting down or reducing the futile cycling. It makes you run through stored fat more slowly.  Which is also a reason that weight loss slows down as a diet progresses.  At the start, there is a lot of futile cycling; as the diet wears on, it shuts down.
    Hope this helps.
    Keep me posted as to how you’re doing on the IF. May all your cycles be futile.

  26. Just finishing up our first fast day. Not so bad, really, but of course I think that’s because I have precisely the portion control issue mentioned in an earlier comment (had a LOT of steak with butter sauce, along with about three bowls of onion soup for dinner last night) 🙂
    I managed to scrape myself off the couch and hit the gym as well, where I did high-impact interval training on the elliptical. That’s doing 30 seconds slow followed by 30 seconds of sprinting, for about 10 or 15 minutes. I came across this training technique several years ago, and though I forget if there was any real clinical evidence, the one thing that stuck with me was a point the author made: who looks more fit, a sprinter or a marathoner? Not very scientific, but interesting to think about.
    After I was done, an interesting parallel occurred to me. Intermittent fasting, the slow-burn weight program (which I’m also starting), and the aforementioned high-impact interval training are all after a kind: occasional periods of intense short intake/expenditure of energy, followed by long periods of rest. Compare to a cow, which spends it’s entire waking day pretty much eating and walking.
    Anyway, that’s been bouncing around in my head all day, just had to get it out 🙂
    Hi Dave–
    Feel free to expound here anytime.

  27. Hi Dr. Mike,
    Stumbled to your site yesterday while researching IF.
    Love it.
    Age 51, bodybuilder. Have eaten protein/ fat/ low carb for 20 plus years.
    I typically low carb it Mon.- Thur.,
    then low carb Fri. through Sun., with evening carb ups.
    Comment about IF- the great trainer & natural bodybuilder, Vince Gironda, achieved some of his greatest results living on 1 meal a day!
    Guess what it was?
    Steak and eggs.
    He stated that this meal satisfied him for the whole day, while retaining his muscularity. Gironda was considered a “freak” who never won a bodybuilding contest in the 50s or 60s, as he was considered too muscular. And he abhored the use of steroids!
    His “definition” style diet consisted of NO CARBS.
    Now my gameplan and questions:
    I have no problem going the whole day without eating. I’ve done it before and did it yesterday and it was quite easy. I was quite energized, really.
    I’m going to do IF Mon.- Sat., low carb straight through to Friday evening and then have my “comfort” foods Fri.& Sat. nights.
    Comfort foods include plenty of fiber, protein and complex carbs. No candies, cakes.
    I’ll reserve Sunday for eating normally throughout the day– protein and low carb w/ an evening carb up w/ lots of protein and fiber.
    I want to become as muscular as possible for the summer. I reached 8% bodyfat last year and would like to do even better this year.
    Do you feel that IF is appropriate for this goal-to become as muscular as possible?
    Would you recommend skipping my typical post- workout meal of whey protein and simple carbs, so as to extend the “metabolic momentum” created from the workout?
    What about taking BCAA after the workout as an option and do you recommend skipping the BCAA during the IF period?
    Thanks for your time!
    Hi Jack–
    Interesting questions.  I don’t have a lot of experience in hard core bodybuilding, but I do know someone who does.  And he assures me that the IF regimen will do the trick.  I would try skipping the whey/simple carb regimen right after the workout and see what happens.  Same with the BCAA.  I’m not a particularly big fan of BCAA because it’s hard to get enough of them in supplement form.  As far as building muscle is concerned, the most important BCAA is leucine, and based on all the research I’ve seen, it takes from 8-12 gm per day to do what you need to have done, which doses are tough to get in supplements.  Meat and dairy products (especially whey) are rich sources of leucine.  It takes about 100 grams of meat or dairy protein to get the 8-12 gms of leucine needed, so on your eat days, you need to make sure you get plenty.
    Hope this helps.  May inspire me to do a post on leucine soon.

  28. Dr. Mike,
    Thanks for your suggestions!
    I do have a very affordable BCAA product from Biotest & 3 tabs provide me w/ 1.62 grams of L-leucine,
    0.9 grams of L-isoluceine and 1.08 grams of L-valine.
    With those numbers in mind, do you think I would still be wise to avoid the BCAA, post workout?
    Also, would you advise taking the BCAA during the day, while IF? Am I hijacking the fat burning benefits by dosing on the BCAA?
    FWIW- I took 4 tabs (6.48g of L-leucine) every 4 hours– (7am, 11am and 3pm)on Monday and felt a bit less hungry than on Tuesday, when I didn’t take any until 5:00 P.M.
    Just a bit “paranoid” about losing muscle.
    My daily evening feed does include a whey/ micellar shake w/ water, providing 40g of protein w/ salad, some nuts, some beef or chicken, cottage cheese or low carb yogurt & an Atkins bar.
    Best Wishes,
    Hi Jack–
    The IF is pretty new, so there isn’t a whole lot of data yet.  I can’t see a reason that taking the BCAA supplements after a workout would hurt.  I wouldn’t take the simple carbs, though.
    Keep us posted.

  29. Dr. Mike,
    Above, you note that body weight is often said to determine basal metabolic rate, but here are links to abstracts of several papers that related it more closely to lean body mass:

    “Resting metabolic rate was highly significantly correlated with body weight, surface area, creatinine excretion and lean body mass….”

    “…fat-free mass (FFM) represents a key determinant of the magnitude of resting metabolic rate…”

    “Lean body mass was found to be the single predictor of BMR.

    Hi PubMed diver–
    If you want to split hairs BMR is probably more closely related to fat-free mass than to total weight, but total weight is much easier to determine accurately and is a pretty good proxy.
    Thanks for the links.

  30. This way of eating really works! I’m a type 2 diabetic, on 2 500 mg Metformin daily, following Dr. Richard Bernstein’s low carb plan. Mostly my FBGs are usually in the range of 106-115. About a week and a half ago on a Sunday, I had a lowcarb breakfast of some whitefish and cream cheese on 2 wasas. I did not eat lunch or dinner on that day. The following morning I had breakfast around 9 a.m. — about 24 hours after the previous breakfast. Since that time, I have seen FBG readings of 89, 92, 97 and also much better readings throughout the day. I think I may try to do this again.

  31. I am working on Intermittent fasting. I have been doing dome form of fast for the past 4 weeks. I make sure that during my feeding periods I eat lots of protein and fresh veggies and fruits ( all low carb ). My appetite has improved. In the past, I would eat before work, at 6:00 AM. By the time it was 10:00 I was ready for lunch. I was also ready for a second lunch 😉 by the end of the work day and I would eat a big meal once I got home. Then, when it was time for dinner, at 6:00 I ate again. I ate 4 decent size meals a day. Now, by fasting, I go for atleast 14 hours without eating.It seems to give my body the time that it needs to digest and fully process each meal. This helps me to keep my meals down to 2-3 a day. When summer comes, I will have a lot of off time where I can go longer without eating. I am not diabetic but I have had some very distinctive symptoms of hypoglycemia long before I started Atkins. Fasting has not caused my symptoms to return and I am sure that what I eat defines this. I am more alert by doing this and the longer I do it the less fearful I am of going without eating. Afterall, if I really need to eat, the food is there. I must add that I lost 8 lbs since beginning this 4 weeks ago. I do believe that no matter what diet we do, we just eat too much. Also if you eat with to keep your insulin levels in top shape, you will choose better food to eat. I remember my first hypoglycemic episode after eating pancakes for breakfast.The worst time to eat a sugary carby meal is right after a fast. My body is the best teacher. I will let you know what happens in the months to come, Doc.
    Hi Mary–
    Thanks for the report.  Please do keep me posted as you progress.

  32. In addition to my last post, I have to add that the most beneficial fast breaking meal has been liver and eggs :-0. I feel extrememly revved up and I can go further into the day without hunger.

  33. Hi,
    I am intrigued by this.
    I’m basically fasting for 18 hours and eating for 6 hours each day, eating only lunch and dinner each day, sometimes a snack in between. Does that give benefits?
    The stress of caring for 3 small children is relieved somewhat by 2 nice sized meals per day, instead of 3 smaller ones, one of which (breakfast) I am not even hungry for. I’m pretty normally weighted now…a few more pounds off would be nice, though.
    Hi Elle–
    I’m sure it gives health benefits.  But you’ll have to be the one who tells me whether it works for getting off the last few pounds. 

  34. Hi Dr Mike,
    Wanted to give you an update about my venture into IF, combined with LC.
    After 2 weeks, I can honestly say I feel wonderful on this 18/6 schedule! Yesterday, attempted 23/1, but didn’t quite make it, ended up with 21/3 but that’s OK. I like listening to my body, and I got pretty uncomfortable about 3 pm, so I had a snack.
    I’m going to work up to 23/1 on the days my airline pilot DH is home (less stress on those days! LOL)
    I have also lost a couple of pounds!
    Anyway some us at LC BB were wondering: While IFing, do we still need to ensure we get our protein minimum as per PPLP?
    Thanks so much!
    Hi Elle–
    My recommendation would be to get plenty of protein on your eating days.

  35. Hi Mike:
    I have been following the IF Fasting for 3 weeks with no problem with the on & off eating schedule, but my Hair starting falling out big time.I am a very active 72 yr old women which maybe the age could be the problem,is there anything that I could supplement with to stop this? Thank You. Pat
    Hi Pat–
    Don’t worry about the hair loss.  It’s not really hair loss that you’re seeing; it’s a regrowth of new hair pushing out the old, dead hair.
    Here’s what’s probably happening:
    Often when people start a new dietary regimen, the hair follicles (not all of them, but a lot of them) shut down for a day or two.  When this happens, the hair that has been growing from that hair follicle quits growing and dies.  As soon as the follicles reactivate a new hair starts growing and pushes the old one out.  As the old hairs are pushed out by the new hairs, these old hairs come out in the shower, during combing, and just fall out by themselves.  People who have this happen to them, understandably, view it as a hair loss.  The fact that the hairs are falling out means that new growth is occurring, so don’t worry about it.
    Hope this helps allay your worries.
    Keep me posted.

    1. hey mike
      I think its a bad thing you advice Pat not to worry about this.
      Me myself had the same experience, twice now ….
      Everytime I start doing IF, for like 3 weeks. The result is that my hair starts falling out. Even though my caloric requirements are okay, not to low. And eating quite well for my metabolic type.
      yHowever all this good execution, I notice that my hair starts falling out, everytime when ím in the shower and i put my hand through my hair, it leaves like 20 hairs on my hand. This is absurd, not normal at all, even though you lose like 100 hairs a day.
      When I transitioned back to a 6 meal a day setup, kind of paleo with some more carbs. My hair loss suddenly started declining, and eventually like after 2 weeks my hair structure is normal again. So it is easy to always look at the good sides of things.. ways of life, ways to eat. But it is also important to list the risks your taking.
      I do not know what the cons are of IF sofar, i’ve never seen them posted on websites like these. If you would go to a plastic churgeon for a nosejob, wouldn’t you ask for the risks and complications? Why not a topic about that.
      Lets make it objective
      Thank you
      I really like your site, however my complaints 😛 It is negative reinforcement 😉

  36. Hi there, I had a question about the schedule I’m planning on doing – I lift weights as my main/favorite exercise usually in the AM around 7:00. If I have a small pre-workout meal consisting of some whey and an apple at around 6:00, and then have one big post-workout meal after I lift at 8:00-8:30 AM, and then fast for 13-14 hours until about 10:00-10:30 PM and have another big meal, would this be beneficial?
    I’d like to do IF, but I just have to make sure I get my pre/post workout meals in because I know they are important. The meal before I go to bed is just because I have a hard time falling asleep on a completely empty stomach. So basically my daily calories would be split into two big meals and one very small pre-workout meal (because Im afraid to leave that out to keep my strength up when lifting.) Does this sound like a plan?
    Hi Shaina–
    It sounds like a plan; I just don’t know if it’s the best plan.
    When I lift weights I don’t eat before or after.  But that’s just me.  You need to fool around with it to see what works best for you.  I would try not eating before and immediately after to see what happens.
    Keep me posted.

  37. really? I was under the impression that the postworkout meal was like the most important thing ever? I could try skipping pre-workout, but skipping post makes me a little nervous, though I could try it out one day. I’ll definitely keep you posted though.
    I’ll wait to hear from you. 

  38. Hi Dr Mike,
    Just wanted to update you again at 1 month into LC/IF:
    I LOVE IT! I have relaxed my “rules” in that now I just wait until I feel strong hunger to eat without regard to fasting times or eating times. Sometimes I feel strong hunger again that same day, sometimes not until the next day.
    FINALLY, I can eat as much as I need to feel satisfied! lol I never felt like I had the freedom to eat a big meal when I was eating 3 times a day. I love big meals!
    I feel strong in my workouts, I’m sleeping well at night, and just overall doing well and enjoying it very much.
    The best part is I’ve lost 5 pounds in the last month and am now in sight of what I consider to be my “best weight.” Yay!
    Thanks again!
    Hi Elle–
    Thank you for the update.  I’m glad to hear you’re doing so well.

  39. Hello, Dr. Mike.
    First of all, let me say that I’m a big ‘fan’ of your Protein Power plan! It is the only diet I have ever had any success on in my entire life. (Trust me, I’ve tried most of them!)
    Second, I have been keeping up on all the forums, blogs, studies, and articles on intermittent fasting. I’ve been wanting to attempt a 23/1 fasting/eating schedule. The studies are too promising health-wise to ignore. My problem has been a drop in my blood sugar (I’ve battled this for years) at around 2:00 or 3:00 p.m. when it is virtually impossible for me to eat. I would like to eat my meal in a one-hour (no more than three-hour) window.
    Do you think that consuming too many diet sodas during my fasting hours could be affecting my blood sugar in this way? I drink about 72 oz. before 5:00 p.m. most days.
    Thanks so much for your time!
    -Carol Ann
    Hi Carol Ann–
    I wouldn’t be surprised if your diet drinks weren’t knocking your blood sugar down a little.  Here’s why.  Insulin is released from the pancreas in two phases: phase 1 and phase 2.  Phase 2 insulin release occurs when the blood sugar actually starts to rise after you’ve eaten something with carb in it.  Phase 1 insulin response, the so-called cephalic response, occurs before the food is even eaten.  Phase 1 is driven by the brain and occurs when the brain thinks something sweet is coming along that will run blood sugar up, in other words, it tries to give insulin a little head start.  When you drive by a bakery and smell the freshly baked stuff, you get hungry.  Why?  Among other reasons because your brain thinks you might be going to eat some of that bread and so sends a signal to the pancreas to get ready.  The pancreas responds by releasing just a touch of insulin.  If no bread is forthcoming, this touch of insulin causes the blood sugar to fall.  A falling blood sugar is one of the strongest hunger stimuli, therefore you’re really hungry shortly after driving past the bakery.  I suspect the same thing happens with a lot of people when they drink diet drinks.  The brain senses the sweet taste, figures that a load of sugar is coming, a tells the pancreas to get ready, which it does by squirting out a little insulin.
    I don’t know if this is what is happening in your case, but I would bet on it.

  40. Hi Dr. Mike,
    On the fasting days, I’ve had little trouble sticking to noncaloric beverages and supplements, but I do have a question regarding hunger. I follow a low carb eating plan and although I keep carbs low, I occasionally get hungry – not just a little bit, but in a loud, distracting way!
    In the past, before IF, I was able to utilize Psyllium husks or Chia seed gel mixed in a glass of water to quell hunger pangs. I find that a serving of soluble fiber keeps me sated for several hours. Since most low carb eating plans advocate that fiber carbs “cancel” themselves out – what would be your opinion of consuming a fiber-based supplement to quell hunger on fasting days? Do you think it might negate the health benefits of IF? I could do an experiment and see how it impacts weight loss, but I am more curious about the internal health parameters that we can’t as readily observe? Your thoughts appreciated.
    Hi Lynn–
    I posted on fiber and its affect on the GI tract a while back.  If you use the search function you should be able to find the post.  I’m not particularly a big fan of fiber – even the soluble kind.  It works by damaging the lining of the intestines and making them produce protective mucas much in the same way that smoking harms the lining of the respiratory tree.
    I don’t know that the hunger-abating effects of fiber can overcome the negatives – at least for me.  Plus, although the fiber doesn’t really stimulate an insulin response, it does contain calories.  The large intestine converts fiber to fatty acids, which are then absorbed. 

  41. Hello Dr. Mike,
    I have been reading the IF topic on your blog with great interest.
    I am attempting to sum up your thoughts on metabolic rate as follows:
    Metabolic rate is primarily determined by body weight, but also to a lesser extent by physical activity level and the thermic effect of food. At the same time, calorie restriction over time can become a factor as well.
    Does that pretty much capture it?
    Thanks, Lynn
    Hi Lynn–
    You’ve pretty much captured my thoughts on metabolic rate except for the part about caloric intake.  I’m not sure that caloric intake (other than its thermic effect of food role) has much affect.  If you reduce calories substantially, you lose weight, which does affect metabolic rate.
    Is that all clear as mud?

  42. Thanks for your comments Dr. Mike, much appreciated and your vacation photos are wonderful, by the way 🙂
    One more thought on some of this – I recall in the Protein Power books the recommendation that a daily carb allotment be evenly spread amongst the multiple daily meals in order to avoid a spike at any one time.
    If one is doing IF and eating one primary meal per 24 hour cycle, under those circumstances, do you see any issues with eating all of one’s daily carb allotment within a narrower window? I’ve been wondering whether all the other benefits of IF would make that a moot point?
    Thanks again.
    Hi Lyn–
    No, I don’t see a problem with that.  We wrote Protein Power over 10 years ago; I’ve learned a lot since then.

  43. Hi again Dr. Mike,
    A few more thoughts on these topics.
    Regarding fiber, I hadn’t before considered the issue of damage to the bowel lining, good to consider. From childhood, I recall an elderly relative who suffered from something called diverticulitus or (diverticulosis?)….seems to me her diet consisted of little more than fiberless foods if I recall correctly.
    As to IF, it occurred to me over the weekend that the original hunter-gatherers who naturally followed an IF way of eating, were quite physically active.
    In today’s society, most of us are sedentary, although I myself try to get at least 30 minutes of exercise each day, that likely pales in comparison to these original IF eaters. Do you think that could have any impact on how the body responds to IF? In other words, do you suspect there’s any correlation between activity level and IF with regard to its efficacy?
    Thanks again.
    Hi Lynn–
    I don’t know that hunter/gatherers were as active as many people think they were.  In studies done on aboriginal Australians where indigenous people were taken from towns and reintroduced to a hunter/gatherer  lifestyle, it was found that they lost weight and got rid of their diabetes and high blood pressure all while expending less energy than they had  been doing previously in their more ‘civilized’ lives.
    It doesn’t hurt to exercise, but I’m not sure it confers the benefits most people think it does unless it is hard resistance exercise, which will definitely increase strength.

  44. Hello Dr. Mike,
    So far so good with the IF – Instead of doing 13-14 hour fasts like I previously mentioned, I have been experimenting with just one meal a day (or 23 hour fasts), and I notice if I keep fat high and carbs low, I have almost no hunger problems.
    I do have one concern though, I read somewhere that there was a study done on the effect of the time of day that you eat. With 2 groups of people, they each group 1 meal a day consisting of 1200 calories. The ones fed in the morning were said to have lost weight and the ones fed in the evening did not. What are your thoughts on this? Should I be worried about consuming one large meal in the evening?
    Also, what would be the effect of consuming something like 1tbp of coconut oil (pure fat nothing else) before my workout in the mornings? Would this ruin my fast, or is it ok because it doesn’t spike insulin? I’m only considering it because sometimes I am very tired in the mornings and coconut oil seems to get me going and give me energy.
    thanks a bunch!!!!
    Hi Shaina–
    I don’t think it makes much difference when the meal is if there is only one per day.  It might make a little difference if it were eaten in the morning, but probably not enough to make it worth it unless you just want to eat your meal in the morning.  I think the tbp of coconut oil is probably a good idea.

  45. Thanks again!
    I had one more question regarding carbs and IF. I like keeping carbs low because it seems to cause some rebound hunger when I eat too much in my meal. I’ve heard that perpetual low carb intake tends to reduce thyroid output and leptin levels (which is bad, right?). So thats why some people advocate refeeds of carbs every once in a while, like once a week, or once every two weeks.
    Is this really necessary? I mean, I guess it could be like a “cheat” meal but since carbs just end up making me miserably hungry later, I’d rather not do this if I don’t have to. What are your thoughts on this?
    My thoughts on it are to keep the carbs low most of the time.  That’s what I do myself.  If carbs cause metabolic problems, they cause them whether you eat carbs everyday or once per week.  I don’t see any advantage in consuming a bunch of carbs anytime.


  46. Thanks!!
    I have yet another concern that I just thought of – is it possible to stretch your stomach by consistently overeating? When I eat my big meal, I am sometimes painfully stuffed, but I feel like I’m not satisfied until I eat that much (and its within my calories for the day). Am I stretching my stomach, and should I be worried about this? Or is that just a myth?
    Thanks so much for answering my questions!!
    That’s a good question, and I don’t know the answer off the top of my head.  If you eat a large meal one day, then don’t eat for a day, I don’t think you run the risk that you would by eating large meals constantly.  Having said all that, I don’t even know for sure that the whole stomach-stretching idea has any basis in fact.  I’ve never really seen any scientific information on the subject.  It will give me something to look up once I get home.

  47. Dr. Mike –
    Thank your for giving me the tools to make a change. IF has given me the oppertunity to recognize some disturbing behaviors I have aquired. IF has allowed me to stop the grazing of unhealthy foods without thought. IF has required me to think about what I’m going to eat and why. IF gives me the time to reflect and plan. I believe this way of eating is allowing me to change my addicitive emotions towards food.
    Protein Power made a difference to me when your book first came out and you continue to guide me in my quest for health.
    Thank You.
    Thank you for the kind words. Sounds to me like you had to do all the work.

  48. Great and interesting thoughts shared. I’m wondering about the effect of two things during IFing–intake of Glutamine (should I be afraid of it?) and low-dose metformin taken for anti-aging purposes.
    Any input on these?
    I have been taking metformin in the morning, and then have been unhungry all day. I eat in the late afternoon only because I feel I should. My weight is stable and I’m feeling fine, so far, even though I would like to get rid of 15 pounds.
    Thanks for your book and for sharing your continuing growth and exploration.
    Glutamine shouldn’t be a problem, but I have a problem taking pharmaceuticals unless absolutely necessary. I’ve read all the reports about low-dose metformin as an anti-aging product, but I wouldn’t take it. But that’s simply my bias. If it works for you, who am I to naysay it.

  49. you know, if you want an anti-aging pill, why not try slow burn weight lifting? if I lay off lifting for a week and a half or so, and then have a good long slow burn session, the next morning, I can see the effects of that rise in human growth hormone in my face. My daughter has noticed it in her dad as well as me. gotta trust those sharp young eyes. she wanted us to run a 10K with her on Thanksgiving, and while that is longer than we usually run, we went with her. it was physically and psychologically stressful for us. it is unnerving, when you run with at most 2 other people, to all of a sudden be in the midst of thousands of others running on narrow suburban streets. the silence, except for the sound of all those pounding running shoes, and thoughts of stumbling and falling and landing at the bottom of an immense pile of tripped runners is very disquieting. needless to say, you’re careful, very careful, of your footing. the day after Thanksgiving, with the immense spike of HGH that we had experienced the day before, we looked like we had facelifts instead of a run. we don’t look that bad usually, thanks to Dr Mike, MD and PPLP.
    something that I do not know if paleo-whatevers have a good handle on, is the span of time that humans were increasing in numbers, and large food animals were decreasing in numbers. could a case be made for intermittent fasting as part of our development, as we had to travel farther for game, and large kills were spread out farther, time-wise? Early observers of American Indian life always stress Indians’ periods of near starvation as large game was scarce and small game required so much energy to acquire.
    robyn cardy
    I’m sure that intermittent fasting on a regularly irregular basis was a part of our nutritional heritage.

  50. Just wanted to report that I continue to feel fine, and, since I started IFing, I have gotten rid of 10-12 lbs. I expect to get rid of another 8-10 lbs in the next coupla months.
    I’m also taking many supplements, which perhaps, slows down my weight loss a bit. OTOH, I am at an upper age level, so it behooves me to lose weight slowly (slow and steady, with persistence).
    Thanks for all your educational information!

  51. Dr. Eades,
    I just read your post about intermittent fasting which led me to this article.
    I am 18 years old and weighed 225 pounds when I was 16. A change in lifestyle led me to lose weight. Currently, I am 165 pounds but I still have high fat content on my buttocks, thighs, stomach, and arms.
    I am interested in beginning Intermittent Fasting for all the health benefits. However, I am not so familiar with low-carb after the whole Atkins scare. It seems to me that low carb diets are good as long as they are followed properly.
    What are the guidelines for a proper low-carb diet? Meaning, am I allowed to eat cheese and butter and high fatty foods? If I DO eat carbs, what kind of carbs should they be? e.g. fruits, vegetables? Are whole-grain carbohydrates OK?
    I want to lose/burn the fat that I have in various regions of my body but more importantly, feel strong and healthy.
    Hi Violet–
    It’s beyond the scope of the comment section of this blog to lay out all the guidelines for a proper low-carb diet. It took us the entire book Protein Power to do it. I would recommend that you read that book or the 30-day Low-Carb Diet Solution for everything you need to know. You can also get on the Protein Power forum (link at the top of this blog) and get a lot of help and a lot of answers.
    Good luck.

  52. Dr. Eades,
    I just read your article which states that Intermittent Fasting isn’t all that good? I still want to give it a try but now I am unsure as to what you think is best as of now.
    It works great for a lot of people; not so great for others. The only way to find out is to give it a try.

  53. This link ( no longer works– is this interview still available?
    Also, Seyfried has continued to publish interesting studies, see for example:
    Epilepsia. 2008 Nov;49 Suppl 8:114-6.
    Targeting energy metabolism in brain cancer with calorically restricted ketogenic diets.
    PMID: 19049606 [PubMed – indexed for MEDLINE]
    Nutr Metab (Lond). 2007 Feb 21;4:5.
    The calorically restricted ketogenic diet, an effective alternative therapy for malignant brain cancer.
    PMID: 17313687 [PubMed]
    I checked and the link doesn’t work. I’ve switched blogging software since I wrote that post and many of the links pre-switch don’t work. I’m out of the country right now, but when I get back, I’ll work on getting that link operational.
    Thanks for the heads up.

  54. Jacob asked: “What effect would Intermittent Fasting have upon one’s weight lifting performance?”. MRE answered: “I’m going to post on these very issues soon. Stay tuned”
    My question: was it done already? or did it get to the bottom of the stack in place of more important stuff?
    No, it hasn’t been done. I want to do a comprehensive post on it when I do it, which means digging out and critically reading all the scientific literature since I last posted on the subject, and I just haven’t had the time.

  55. Absolutely amazing! I never heard of IF until I recently delved into a low carb way of life. I have in the past utilized fasting for therapeutic reasons, sometimes at great lengths! IF sounds much more natural, and it’s definitely more practical in today’s modern world. I think it’s only natural to want to incorporate IF into any lifestyle, especially low carb, to make it much healthier.
    Thank you, Dr. Eades, for putting this information out where I and others have been able to read it and become more aware and knowledgeable. I am looking forward to reading more of your blogs.

  56. I have been doing IF for over 2 1/2 years. I do it on a daily basis. Basically I eat 2 meals one day and alternate by eating one meal the next day. My diet is low carb/high fat/high protein. I am doing great. There is some concern however with my blood glucose that I am not really worried about. It jumped relatively high when I had a glucose tolerance test.. I actually believe that I overfasted for the test. If I understand correctly fasting should be around 10-12 hours and I fasted for about 14 hours before coming in for the test. I will see my doctor at the end of December and discuss my results. If he is worried, I am going to request another test. Other than that I am in tip-top shape.

  57. Dear Dr. Eades,
    Thank you again for – again – providing a great deal of valuable information. I have been following your blog for about a year now. I have been on a moderate (low GI) carb diet for several years with ample protein and emphasis on getting my fats right. With such a diet I’ve been able to keep my weight/performance ratio good – endurance running and mountain biking.
    As I discovered protein power and other ketogenic diet approaches last year I tried the keto approach and it brought down to under 70kg for the first time in my adult life in 3 weeks (weight loss of about 5kg ). I sure got lean, but of course a lot of that lost weight was water/carbs. I realized that my anaerobic fitness level decreased noticeably as there were no carbs for fuel. So, there was the catch..
    Now I have been recently reading about intermittent fasting and after couple of 20hrs or so – once a week fasts I can say it’s really working well for weight management. I haven’t been running much lately (apart from one 15km race), so I can’t say much about how my clycogen stores are affected. That said, I am curious how fasting metabolism works with regard to low carb diet (vs just normal keto diet without fasting).
    – Does 24hr fast first use liver/muscle clycogen for fuel (as in keto induction) and only after those reserves are used would turn burning fat? The reason why I am asking is I would like to stay on low carb diet (but still enough to keep my muscles loaded) but be able to partake on endurance outdoor sports. I have read the GI of different carb foods is not so much of a concern when IFing, but low carbing has helped with bloating and joint function as well (not to mention flue free winters here in cold and dark Scandinavia!)
    P.S. As a foodie and industrial designer I have been very pleased to read about your and MD’s sous vide developments! Great stuff!

  58. Apparently Do Eades has abandoned this blog and is no longer interested in questions about IFing. He’s found other fish to fry and pursue.

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