Evidence Mounts on the Therapeutic and Healing Benefits of Fasting

I used to blog about this all the time. About 230 posts going back to 2008 that are either about fasting, or mention it in some way.

There were several things that intrigued me. Off the top of my head:

  1. Makes weight loss pretty easy
  2. Once adapted to it, most people find enhanced mental attitude and clarity
  3. Many religious institutions have various fasting regimens. Hmmm…
  4. It may confer the hypothesized longevity benefits of chronic caloric restriction diets, without being chronic, but acute.
  5. It may protect healthy cells against the ravages of chemotherapy while weakening cancer cells.

It’s that last one I blogged about way back here, more than 6 years ago: Counterintuitive Cancer Therapy.

Fasting for two days protects healthy cells against chemotherapy, according to a study appearing online the week of Mar. 31 in PNAS Early Edition. Mice given a high dose of chemotherapy after fasting continued to thrive. The same dose killed half the normally fed mice and caused lasting weight and energy loss in the survivors.

Fortunately, Dr. Longo didn’t sit still on this: Fasting triggers stem cell regeneration of damaged, old immune system.

In the first evidence of a natural intervention triggering stem cell-based regeneration of an organ or system, a study in the June 5 issue of the Cell Stem Cell shows that cycles of prolonged fasting not only protect against immune system damage — a major side effect of chemotherapy — but also induce immune system regeneration, shifting stem cells from a dormant state to a state of self-renewal.

In both mice and a Phase 1 human clinical trial involving patients receiving chemotherapy, long periods of not eating significantly lowered white blood cell counts. In mice, fasting cycles then “flipped a regenerative switch,” changing the signaling pathways for hematopoietic stem cells, which are responsible for the generation of blood and immune systems, the research showed.

We could not predict that prolonged fasting would have such a remarkable effect in promoting stem cell-based regeneration of the hematopoietic system.

The study has major implications for healthier aging, in which immune system decline contributes to increased susceptibility to disease as people age. By outlining how prolonged fasting cycles—periods of no food for two to four days at a time over the course of six months—kill older and damaged immune cells and generate new ones, the research also has implications for chemotherapy tolerance and for those with a wide range of immune system deficiencies, including autoimmunity disorders.

“We could not predict that prolonged fasting would have such a remarkable effect in promoting stem cell-based regeneration of the hematopoietic system,” said corresponding author Valter Longo, Edna M. Jones Professor of Gerontology and the Biological Sciences at the USC Davis School of Gerontology and director of the USC Longevity Institute. Longo has a joint appointment at the USC Dornsife College of Letters, Arts and Sciences.

“When you starve, the system tries to save energy, and one of the things it can do to save energy is to recycle a lot of the immune cells that are not needed, especially those that may be damaged,” Longo said. “What we started noticing in both our human work and animal work is that the white blood cell count goes down with prolonged fasting. Then when you re-feed, the blood cells come back. So we started thinking, well, where does it come from?”

Sounds a lot like autophagy, another term that’s in lots of my posts going back 6 years.

Interestingly, a chronic ketogenic diet has been touted as an effective therapy for both cancer and epilepsy, and with some evidence to justify hypothesis forming and testing, a good thing. But has it panned out? Moreover, is it less effective than ACUTE ketosis (AKA: an extended fast)? If something is good, is more of it and all the time necessarily better? Does disregarding delicate balances either way get you into trouble?

Angelo Coppola, an honest inquisitor after my own heart—with no turf to protect with stinky obvious bias—recently dropped a comment on the changing landscape with regard to chronic ketosis vs. more effective therapies.

Re: Cancer & Epilepsy

Dr. Gonzales Dismantles the Ketogenic Diet for Cancer

This Dr. claims to have worked closely with Atkins and that Atkins tested a ketogenic approach on cancer patients but failed to show benefits.

~ The surprising story of medical marijuana and pediatric epilepsy: Josh Stanley at TEDxBoulder.

~ An incredible story about the effects of CBD (a non-psychoactive compound in cannabis) on epileptic children. From CNN:

“Paige took her daughter to Chicago to see a Dravet specialist, who put the child on a ketogenic diet frequently used to treat epilepsy that’s high in fat and low in carbohydrates. The special diet forces the body to make extra ketones, natural chemicals that suppress seizures. It’s mainly recommended for epileptic patients who don’t respond to treatment.”

The diet helped control Charlotte’s seizures but had a lot of side effects. She suffered from bone loss. Her immune system plummeted. And new behavioral problems started popping up.

“At one point she was outside eating pine cones and stuff, all kinds of different things,” Matt said. “As a parent you have to say, let’s take a step back and look at this. Is this truly beneficial treatment because of these other things?”

Two years into the diet, the seizures came back.”

Go ahead and sort it all out, pass it on to folks who might need it.

Here’s my random thoughts about fasting:

  1. Except for fat loss, it ought not be about under eating, but crowding the same amount of food into a shorter time.
  2. I’d rather see a person do a 4-day fast and eat regularly the other 26 days of the month, than a weekly fast.
  3. I’d rather see a person do a 2-day fast and eat regularly the other 12 days of a fortnight, than a weekly fast.
  4. I’d rather see a person do a 30-hr fast weekly than do a daily fasting window, with one exception: a disciplined Leangains-styled protocol that involves holy shit heavy lifting 3 times per week, and eating your ass off, with everything counted, in an 8-hr window every day.
  5. Fasting can be seductive, in that it can gradually adapt you to chronic under eating as you get used to it and plug into the euphoria it can induce. Chronic under eating comes with a whole host of problems, not the least of which is that your body gets very good at making you not exert much energy, all while it guards every molecule of energy it can keep. In short, it can really mess up a metabolism, along with hormonal regulation. I think this was what a lot of women predominantly experienced back when intermittent fasting was all the rage.

Alright, no go empty your fridge and toss it in the trash. Starve.

Richard Nikoley

I'm Richard Nikoley. Free The Animal began in 2003 and as of 2021, contains 5,000 posts. I blog what I wish...from health, diet, and food to travel and lifestyle; to politics, social antagonism, expat-living location and time independent—while you sleep—income. I celebrate the audacity and hubris to live by your own exclusive authority and take your own chances. Read More


  1. Ankleface Wroughtlandmire on July 9, 2014 at 17:58

    When that study about fasting came out about a month ago, I decided to try it to see if it would have any effect on rheumatoid arthritis symptoms. I’ve been strictly following a very healthy diet (basically the Perfect Health Diet + beans and lentils) and am also using resistant starch and probiotics. I wasn’t seeing noticeable improvement after months of following this regimen. But then again I didn’t really expect to after years of bad eating. So when I heard about the immune system “reset” via fasting, I decided to give it a go for three days. And you know what? It helped. A lot. A month after the fast, energy levels are much higher, pain and swelling are under control, and sleep quality has improved a lot. I’m pretty impressed. I hated every minute of the fast, but unfortunately it looks like it helped and should probably be repeated. 🙁 😉

  2. Nick on July 9, 2014 at 19:17

    Are there any guidelines for fasting? Just, drink water and that’s it? Or are other non-calorie substances good too? i.e., potato starch, supplements, etc. I remember seeing on, Paul recommended something like a coconut oil and cooked cranberries “soup” while fasting.

    • Ankleface Wroughtlandmire on July 9, 2014 at 19:23

      Even if it’s a true water fast, I would say that the most critical thing is a bit of sea salt during the fast to avoid water poisoning from lack of electrolytes.

    • MycroftJones on July 9, 2014 at 19:57

      As per the teachings of Carey Reams and many others. Even Matt Stone, that wayward son, retains a lot of RBTI knowledge mixed into his teachings:

      Your concept of keeping electrolytes topped up is good.

      Stay away from sea salt; it is only 70% sodium chloride, and 30% “other” stuff… the “other” stuff being the salts that your kidneys are busy trying to flush OUT of the body. Give your kidneys a break.

      If you have dry mouth, stop the sea salt and use sodium chloride. Works for a lot of people.

      Minerals are important, but have to be in a form your body can use. The beneficial minerals in sea salt are not in the format that your body likes to pick up.

    • marie on July 9, 2014 at 20:36

      I don’t know why women are so afraid of fasting, it makes no sense whatsoever – it’s in many cultural/religious traditions and certainly women were not exempt (!), unless pregnant or breast-feeding. In fact in most cases they were responsible for the family’s adherence to the fasts.

      I know about the hormonal mechanisms hypothesized to be affected negatively “for women”, but I think that maybe obese, PCOS and/or thyroid-troubled women are not the norm from which to extrapolate to the majority of women?

      I was raised in such a tradition, I have incredible immunity (traditional cuisine is partly responsible for that), metabolic flexibility, endurance etc. when I have adhered to the tradition.

      In fact the only times I didn’t enjoy robust health was when I deviated from that regimen/cuisine two decades ago during my ‘modern’ college-student days and again briefly about 8 years ago where I gained some 20lbs. I lost it the following year by reverting again to the cyclic fasting and traditional diet.

      Fasting does wonders too for mitochondria, I can attest to that, my thighs still twinge when I remember the biopsy needle. Together with HIIT (which also has positive effects on mitochondrial biogenesis and efficiency), fasting is credited with saving my life 18months ago from severe hypoxia.

      Richard, I agree as far as my experience goes, 36-48 hours twice a month is maybe ideal for ‘maintenance’/long term.

    • MycroftJones on July 9, 2014 at 21:40

      A body builder commented anonymously that he fasts 3 days every 2 weeks. Perhaps that is pushing it, but probably does no harm. Marie, you are Greek Orthodox, right? Fascinating posts. If you had to summarize your cycle of fasting, how would you describe it? I think you are talking about more than just eliminating meat for the 40 days of Lent?

    • marie on July 9, 2014 at 22:18

      Well, I’m a bit of a mutt with French ancestry on one side, but yes, by far mostly Greek. The fasting was learned from, or better yet ‘imprinted’ by, orthodox grandma, she was from Crete no less.

      It used to be certain days of diet restrictions every month involving fish, vegetables, legumes, some days prohibited meats-dairy. These were followed by 2-day water fasts that led up to the more major religious celebrations/feasts. Or as we kids enviously called them, ‘coffee fasts’ – it was common for the grown-ups to have black greek coffee (‘turkish’, espresso-like).

      The fasts are always, and I do mean always, broken with fatty meat/organs and eggs, first.
      For example on resurrection midnight. The feast generally follows the next day (about 12hours later).

      I am not at all religious and in college years dropped it, only to watch health deteriorate to ‘normal’ aches-pains, colds-infections, energy waning, weight fluctuating etc. Didn’t relate the two until I started reading research, whereby I promptly returned to the fold 🙂
      The second time I dropped the ball nearing age 40 was brief and I had no excuse. Fixed that quickly.

      In latter years I do only the ‘coffee fast’ : 24 hrs if it’s just a hack because I have a long day and need the clear head and afternoon energy boost (whereby I get even better boost with coconut oil in coffee twice that day).

      Otherwise my maintenance cycle is 36-48 hrs twice a month. It comes naturally, I don’t watch a calendar.

      There’s a rule of thumb among Cretans and Aegean islanders, coastal Med folk and Middle-easterners : fasting comes naturally to a well nourished body.

      This works as a diagnostic actually: if there was no inclination to fast, I have always found something had gone off-track – usually in upstate NY and Canada it was winter vitamin D level.

      Once in a while, just to see make sure that I can, I will do like that bodybuilder and go for day three. That’s definitely a discipline though, not like the 24hrs which is completely natural and the 36-48 hrs which takes some thought but is still satisfying.

      How about your routine? I’ve also asked below I think, why the supplements?

    • marie on July 9, 2014 at 22:22

      Ah, I see answer below now. Thanks.

  3. MycroftJones on July 9, 2014 at 20:12

    I personally, also supplement potassium bicarbonate and citric acid, as well as sodium chloride during fasts.

    I was taking way too little sodium, but after reading Matt Stone’s book, I no longer fear salt. I’m positively Ashkenazi in my salt intake now, and my body temp has climbed to where it should be. Matt Stone has some good information, but you need the right foundation to use it safely. Just so you know, I’m not soapboxing for him.

    In addition to what I get through food, I supplement, whether fasting or not:

    5.1 grams potassium bicarbonate
    5 grams citric acid
    6.4 grams sodium chloride
    8 drops lugols solution of iodine
    plus assorted vitamins and minerals

    In fact, I supplement a lot of vitamins and minerals during a fast. Lately I’ve even experimented with adding in RS during fasts, and it seemed to go well:

    6 grams psyllium husk
    20 grams roasted chicory root
    20 grams unmodified potato starch

    The roasted chicory root is 20-50 percent inulin. I started this thanks to Tatertot Tim Steel. He pointed out on one of Richard’s previous threads that inulin is meant to be together with certain polysaccharides and probably other things. Chicory has the highest inulin content of anything, and contains all the polysaccharides etc that Tim talked about.

    Only warning about chicory: if you are pregnant or trying to get pregnant, don’t use it. It is alleged to be natures own abortion pill. I can’t speak to these allegations, and am interested in any evidence to the contrary.

    When not fasting, I am again following Tim Steel’s comments, I ferment 4 varieties of beans and lentils together for 18 hours, then pressure cook them, then cool them. Then combine them with parboiled rice, also cooled.

    My remaining question for Tim (tatertot) is this: how long does the rice and beans need to BE cool for maximum RS3 formation? Is it instant, as soon as they’ve cooled down? Or do I need to wait overnight? Because I have ways to cool these items down rapidly.

    Now that I’ve fermented the beans and am putting in decent amounts of salt, they seem to keep in the fridge for a long time. They go a (tiny) bit sour, but not in a way that tastes bad. Move over sauerkraut, here comes sauerreis?

    • marie on July 9, 2014 at 21:02

      MycroftJones, “In fact, I supplement a lot of vitamins and minerals during a fast”.
      A hack of some sort for a specific purpose?
      Otherwise, why do you need more than water, or perhaps also some salt if it’s been a hot day or two?

      On the other hand, I do like some unmodified potato starch in water on day two, just because it dampens hunger quite a bit 🙂

    • MycroftJones on July 9, 2014 at 21:46

      Yes. I think water only plus a little salt on hot days is ok for most people. I’ve come from a situation of very low mineral reserves, brain fog, low energy, slow metabolism, etc. After 3 months, my pH has finally stablized to the point that I have cut my vitamineral mix to 1/3, and I feel pretty good most of the time.

      It is July, lots of sunshine and hot weather, so I will find out if my improvements are seasonal or due to the fiba-vita-mineral in a few months.

      I took soylent as a starting point, removed all the carbs and protein and canola oil, boosted a few things like iodine, added a few missing things like D3, K2 and inositol, diversified the forms of calcium, added the 3 forms of fiber and resistant starch, and that is my daily mix. Soylent isn’t available in Canada, so I formulate my own mix. Imagine a proper Paleo, “Perfect Health Diet” version of soylent, with all the macro nutrients taken out.

    • gabkad on July 10, 2014 at 19:06

      mycroftjones, how’s your brain fog, low metabolism etc. now?

  4. Sam on July 9, 2014 at 20:56

    Very wise Richard. Once I found intermittent fasting- and experienced the euphoria, mental clarity, improved digestion that came with it – I was hooked. Not to mention I was ‘bulletproof’ coffee ing it up every morning, so as to make it to the euphoria stage. I am also a carless, retail sales rep.- bike > 2 miles each day and stand/ walk the better half of the day on work days. So, anyways I definitely must have been chronically starved at times- cArbohydrate and calorie – and could have benefited from a less regimented eating routine. Found it so hard to move around, regularly, and must have been in very physiologic energy conservation state. To my credit, i do think the catabolic- anabolic balance is very delicate and hard to pin down. Or you have to find the way stuff 1000-2000 calories of paleo food stuff into your mouth in one sitting. Never easy. Anyways the note of the hour has been eat enough protein and calories to support my lifestyle- in the forms of milk and rice and potato starches. I find the daily fast very seductive-mainly for Digestive matters – but, as you said unless your counting everything, carefully, it can be dangerous. Fast safely my frIends 🙂

  5. tw on July 9, 2014 at 21:25

    Having just completed treatment for Hodgkins Lymphoma, and doing a ton of research prior and during I wanted to offer a few thoughts.

    There are 200 different kinds of cancer and 50 different chemotherapy drugs. There is of course radiation as well.

    Fasting may not be practical in cases where a drug like Dexamethesone is used, which generates insane amounts of hunger. (A drug that helps control nausea) The oncologist told this seemed to assist in the treatment, and they did not know why. Perhaps it mimics a sort of fasting response?

    The chemotherapy drugs are disposed of in 2 ways, therefore if one is unable to take a crap due to fasting, you may be causing additional harm.

    The treatment I received hit the bone marrow, and thus your white count takes a hit. You will not be treated below a certain cutoff point.

    I would personally like to know if exercise promotes more cellular turnover and is therefore effective in helping. It worked for me (an assumption)

    While sugar fuels cancer, glucose is also required for certain white cells to do their job. These are the whites that take the biggest hit under ABVD. This paradox may be the reason that some people have problems while on very low carb diets, as discussed in the Perfect Health Diet as I remember.

    The research is exciting but the vast array of chemotherapies and cancers make it far more complex than the research suggests. Patients should discuss the strategy with their health care team before pursuing.

    The amount and type of therapy is important to know and may not be assisted by this strategy. Physical repair is also aided by eating, and if I could put forward 2 things that many patients might benefit from it would be eliminating grain (to reduce the additional hunger which may be produced by cortisone type medications) and eliminating sugar and instead getting carbohydrates from real food. These two can help reduce inflammation generated by treatment and and keep blood sugar more stable which is likely beneficial.

    My two cents.

    I am fine (10 weeks on) and what I went through was tough, but a cakewalk compared to many. My weight barely changed and the side effects were mostly mild, the last month of 4 was tough but not too bad. I used a PHD style eating strategy without the supplements.

    Being fit and eating “well” and maintaining a solid mental attitude are important factors in a persons treatment and recovery. I don’t know if fasting works, but I did consider it; and due to the hunger being induced by the anti nausea pills, I could not have done it personally.

    • gabkad on July 10, 2014 at 19:22

      tw, thanks. I just learned a lot.

  6. Saraswati on July 9, 2014 at 23:37

    Fasting twice a month is exactly what Hindus do.
    This fast is called Ekadasi and it is supposed to rob the god of Death of his crops of incomers. This fast is supposed to be the best of all fasts. There are exact hours astronomically calculated for this, because you have to do it at a certain time and start eating again during a window of time, which can be missed but you have to go on fasting until you come to the appropriate time again. Ekadasi means “the eleventh”, because you fast on the eleventh day after full moon and black moon, that is twice a month. I suppose this must be the time when something happens “en masse” to the bacteria! More info on timings, which are calculated for each place on the planet, here :
    Maybe fasting is good, but fasting on the right day is even better?

    • ozquoll on July 10, 2014 at 19:25

      Thank you Saraswati, I’d never heard of Ekadasi before so I had a look at that link. Fascinating. The info about the four different types of fasts (water, milky drinks, fruit, & one non-grain meal just before sunset) was also interesting.

    • Ozquoll on July 10, 2014 at 19:27

      Thank you Saraswati, I’d never heard of Ekadasi before so I had a look at that link. Fascinating. The info about the four different types of fasts (water, milky drinks, fruit, and one non-grain meal just before sunset)
      was also interesting.

    • Gemma on July 12, 2014 at 23:54


      Thank you for reminding of the lunar cycles. Yes, the organisms respect them, be it bacteria in the sea:

      or other animals:

      The goddess of healing is happily dancing, joyfully tapping her feet and clapping the castanets 🙂

  7. mehitabel on July 10, 2014 at 00:08

    feb 2011 was a bitch of a winter in illinois….and i fell into a fast — 25 days — water only.
    I had previously fallen into 2 and 3 day fasts…..then fell into a 7 day fast, could have gone longer, but sensed the power of where i was going…..and wasn’t ready. fasting gets down to the the rom, the read only memory on the motherboard.
    Careful how you break the fast….I broke mine with v8 juice and suffered the mother of all gout attacks.

    i gotta comment on coppola’s link to gonzales’ “dismantling of keto diet” on the chrisbeatcancer site.
    Those are all vegan-agenda people.

    Gonzales has blood on his hands for steering people away from productive conventional treatment in favor of supplemental woo.

    If someone is fighting a glycolytic cancer, imo, keto is one of the very most effective adjuvent therapies.

  8. LaFrite on July 10, 2014 at 02:31

    As I said in some previous post, I regularly fast 48h every week (from Sunday evening to Tuesday evening). I usually eat ruminant liver at dinner on Sunday, and restart eating on Tuesday evening with similar stuff (fatty meat, eggs, organs). Surprisingly, this is what Marie’s grandma was doing! For me, it is a matter of “good sense”. I need to feed myself with something nutritious. The fast itself is really peanuts. The only thing I have during these 48h is water, coffee (black) or tea. I don’t supplement for I do nourish myself adequately otherwise. The rest of the week, I eat about one main meal every day, and I make it count, I tell you! The only exception is Saturday, which is generally “binge day”, I eat almost all day long, especially when I am social (family, friends coming over or vice-versa).

    This rhythm seems to be just fine for myself.

    My wife regularly skips breakfast but her IF window is shorter, she usually starts with a lunch. She does not do 48h fat like me, more like 36h. She started on that a while back, and surprise surprise, the combo of good foods and IF + weekly long fast has cured of her PMS and headaches. She was tempted to go low carb a some point, but I convinced her to look the other way (PHD type diet). I am the home cook so in the end, she submitted (quite willingly since I cook some nice stuff for her 🙂 ).

    • LeonRover on July 10, 2014 at 06:12


      You clearly a cheep off GrandMarie’s block.

      :)) :))

    • marie on July 10, 2014 at 10:26

      LaFrite, it’s interesting, I know other people who have independently gravitated to the same routine of 36-48hrs fasts followed by meat-organs-eggs.
      The nutrient dense ‘break’-fast makes sense given current knowledge and is also part of old traditions, but it especially feels good digestion-wise, doesn’t it?
      Besides, who knows, maybe not shocking the fasted system with a sugar rush is a good thing too.

      Meanwhile, hmmm, you have a submissive wife? Oh how little we knew ye, old friend! 🙂

    • Bret on July 15, 2014 at 07:23

      LaFrite, do you notice any specific effects with the coffee with specific regard to the fast? Or are the caffeine effects the same as you experience when eating normally?

      I am starting some IF self experiments, and am curious about what others are experiencing. I like my coffee, but I have heard it tends to induce an insulin spike. I think I would rather be in ketosis for my IFs, for reasons I will explain in a separate comment below.

      Thanks in advance for any perspective.

    • LaFrite on July 15, 2014 at 08:46

      Hello Bret,

      Personally, I feel no different. But the thing in my case is that I hardly have anything when I drink coffee (always black). The rare thing I do is around lunch time, when I would have the occasional slice of gruyère or manchego (but that’s rare).

      I don’t think coffee on its own raises insulin. According to Sisson’s findings – – it may provoke a natural insulin resistance becuase caffeine tends to promote lipolysis via adrenaline increase. But if you eat nothing at all, nothing to care about. When you are fasting, insulin and glucagon are at play to maintain blood sugar anyhow, and I don’t see how these hormones can spike or drop without a significant concentration of nutrients in the blood stream to be dealt with.

    • Bret on July 16, 2014 at 07:50

      Awesome–thanks for sharing!

    • Bret on July 16, 2014 at 08:21

      I would also add this article in JAMA for consideration, since I ran across it afterward. It supports the same reasoning…i.e. coffee does not exert a big effect on insulin levels or sensitivity, but a positive one if any.

    • Brad Baker on July 19, 2014 at 12:32

      I have found that coffee helps lipolysis (as mentioned below) and hence will supply energy and curb a hunger pang if you get one. In the same way, I’ve noticed that physical exertion will do the same thing – kill a hunger pang. If during an IF I get hungry and can bang out a set or two of chin-ups or go for a jog and the hunger goes away withing about 20 minutes.

      Also, I ALWAYS drink coffee before a fasted gym/lifting workout.

  9. Pauline on July 10, 2014 at 06:34

    I posted a comment about fasting here:

    I have began recently re-exploring fasting after experiencing some stiffness with my wrist/hands linked to inflammation. Fasting is usually very good for anyone needing to sort out food intolerances too, which can be the main cause of arthritis. So I have been re-reading Fast 5 Diet and the Warrior Diet, both speak about the importance of fasting for resetting appetite and eating well in that fasting/eating window. Its a learning curve for women especially as we spend a lot of time preparing and sourcing food to provide the best nutrition we can. I think if you are not lucky to be born into a culture that celebrates fasting it can be seen as a form food restriction or denial, but when understood properly and slowly adapted to increasing those fasting periods, hormonally one adapts and so does appetite and hunger too.

    • marie on July 10, 2014 at 10:33

      Pauline, that makes a lot of sense, learning about fasting takes a while when starting from scratch, as does getting past the tendency to confuse it with anorexia or some such.
      Fasting actually emphasizes good nutrition – that might seem paradoxical at first.

  10. Pauline on July 10, 2014 at 06:40

    One of the best books on Arthritis, fasting and the link with food intolerances and healing is this one:

  11. sally on July 10, 2014 at 08:26

    I wish I could remember what Dr.BG has said about fasting in the past. I think she has mentioned that people who have adrenal exhaustion should not fast?

    • marie on July 10, 2014 at 11:40

      sick people as a general rule should not suddenly start any intervention without medical advice and/or some serious research on their own.

      That said, there are several conditions that have been documented to improve with fasting, like the dramatic example of immunity in this post.
      Adrenal exhaustion isn’t one of them, at least up to now.

      However, I tend to keep in mind that the starvation/fasting response is transient acute and that has never shown any evidence of problems short or long term, not on the adrenals nor on any other body system.
      It shouldn’t, we’d be dead without that response.

      The fasting response is simply not the prolonged, chronic stress for which there is indeed evidence of various negative physiological effects.

    • LaFrite on July 10, 2014 at 11:45

      I would also like to add that fasting is often implicitly confused with starving. Chronic starving (aka eating chronically below your nutritional needs) is another beast altogether.

      Fasting means that you are _not digesting_ Your stomac is empty, and your gut is done digesting your meal. It has NOTHIGN TO DO with starving yourself. It just means that your eating rhythm is different than the regular 3+ meals / day. You could eat once every 2 days if you like, but what you eat matches your nutritional needs, then this is not starving.

      On the other hand, you could eat very small meals every 2-3 hours every day, and still be chronically starving 😉

    • marie on July 10, 2014 at 18:16

      Thanks LaFrite, good points!

    • gabkad on July 10, 2014 at 18:57


    • Curious RSer on July 14, 2014 at 17:53

      Useful. Thanks! So having fiber and resistant starch during the fast to feed the gut bugs, though low in calories, would not be seen by the body as being equivalent to fasting, and would likely not yield as much benefit? Or having a spoon of fat with which to consume fat-soluble vitamins such as D and K2 would also reduce the benefit? From the body’s perspective, what differentiates fasting from eating a ketogenic diet? Is it the lack of protein when fasting? Or is it also the lack of carbohydrates and/or fat and/or nutrients?

  12. sassysquatch on July 10, 2014 at 08:45

    I read the Warrior Diet in 2004 or so, and for the most part, have been going with daily fasts of 16 to 20 hours a day, for much of the last 10 years. I disagree with Richard, I believe this is the best way to implement IF. Lately, I’ve been trying to eat within a window of noon to 6:00 or 7:00 pm. Interestingly enough, I had read where Herschel Walker had eaten this way for much of his life. And Herschel was a heck of an athlete with a super muscular physique. He still has a great build. I’m 60 years old, and have maintained my muscle mass from 20 years ago. In some ways, even more muscle. While muscle mass may not be a great indicator of health, it is a reflection of the bodies ability to repair itself. THANK YOU ORI!!

    • Brad Baker on July 19, 2014 at 12:23

      Agreed. Daily IF is the way to go. And I think the smaller you make the feed window the more benefits. Single meal per day is the ideal but hard to get enough calories doing that if you’re exercising. I generally do about a 4-6 hour window. Works great for me (51 years old) combined with just lifting, no cardio, 2-3 days per week.

  13. Chris on July 10, 2014 at 08:56

    What about Beet Kavas or Kraut Juice when fasting? It’s my understanding they have electrolytes. I feel like this could potentially help during the fasting process. But, on the other hand we are introducing more bacteria into our system, is that a good or bad thing? Is there ever a time period when we need a break from even the beneficial bacteria? Also, Beet Kavas is loaded with nutrients, could this make the fasting process less effective?

    My gut tells me that a water only fast would be the most beneficial but next time I fast I’ll try doing it with Kraut Juice or Beet Kavas.

    Anyone ever tried these fermented drinks during a fast?

  14. Jimmy 4 Jesus on July 10, 2014 at 10:57

    Berkhan is like a god to me. I’m totally not gay, but I’d let Berkhan have his way with my ass if he had the need. I respect him that much!

  15. Angelo on July 10, 2014 at 11:40

    It’s worth noting that Dr. Longo was also the lead researcher in “Meat is as Bad as Smoking” study that was published not long ago. I analyzed that research along with Zoe Harcombe when I guest hosted The Livin’ La Vida Low Carb Show (here: . Needless to say, there were some glaring problems with the research conclusions, the Press Release, and subsequently with the way it was reported in the press.

    Also, for what it’s worth, Longo also owns a business that creates vegetarian-based foods that are designed to assist with therapeutic fasting and chemotherapy. Not necessarily a problem…after all, someone in that line of business would be very interested in researching the topic.

    But, it is a potential conflict of interest, and that previous meat/smoking study was very poorly handled.

  16. Pauline on July 10, 2014 at 13:23

    I have been interested in fasting and eating less as overall strategy to a long and healthy life. So if there is a book on fasting I will read it especially if it has been practised for a long time.

    Is about the diet of a group of Greek monks on Mount Athos who practise 3 days of fasting with soups and vegetables and 3 days of eating normally with one day dedicated to celebratory food without any restrictions. They are very young, healthy and active into old age.

  17. Ned Kock on July 11, 2014 at 16:51

    One strategy that mimics more prolonged fasting (e.g., 24h+) is working out not eating anything for about 8 h. You lose some amino acids in muscle with both, but you never lose muscle cells. As long as you don’t do this all the time, the aminos lost are gained back, perhaps with supercompensation.

    • Richard Nikoley on July 11, 2014 at 17:44


      I miss you longtimes. 🙂

  18. GTR on July 13, 2014 at 03:37

    OK, so fasting causes stem cells to turn into immune cells. How does that relate to stem cell exaustion being one of the reasons of dying from old age?

    “Researchers also found that the telomeres on Andel-Schipper’s white blood cells were very short. Telomeres are at the ends of the chromosomes and protect them from damage, but they get a little shorter each time cells divide.

    There may be a limit to how many times stem cells can divide, and possibly they eventually die from division exhaustion. Researchers think it may be possible that the 115-year-old woman died from stem cell exhaustion, which could also be cause of death for many people who live to extreme old age.”

    One of the methods to limit stem cell exhaustion might be to limit mTOR activity, eg. by eating a low-protein diet; just like Rosedale, or Tel-Oren advice?

  19. Bret on July 16, 2014 at 08:04

    Question about ketosis for anyone who cares to answer:

    Do you think most of human ancestry spontaneously ate in such a way that promoted ketosis, or not (and if not, then that arguably ketosis was merely an evolutionary safeguard to survive starvation)?

    In the context of many nutritional ketosis experiments going on in the modern day, a lot of people try to argue that a truly paleo/primal/ancestral diet was one that promoted ketosis, even without fasting/starving. However, I find this illogical, based on the fact that, from the evidence I have seen, most people seem to have much higher B-OHB readings under actual fasting than they do trying like hell to eat tons of fat, minimal carbs, and low protein. The Inuit’s apparent lack of ketosis, which Richard has emphasized often, seems to support this idea.

    I am sure this idea is already floating around out there, so I am not claiming it is original or unique to me. In the process of slogging through the literature (not done yet by a long shot), the idea simply occurred to me. Just curious what others’ thoughts are on the topic.

    • Duck Dodgers on July 16, 2014 at 12:09

      Do you think most of human ancestry spontaneously ate in such a way that promoted ketosis, or not

      You probably already know my opinion on this, but I don’t believe that there is any evidence of human ancestry promoting ketosis in a fed state. Beyond the fact that every human culture revered their carb sources, and beyond the fact that over 100 years of scientific literature on the Inuit has never shown any evidence of ketosis from their diet, this latest uncovered example that Inuit exhibited glucose tolerance from their traditional diet (while Stefansson and Anderson lost their glucose tolerance from their Westernized style of meat eating) only helps confirm that the Inuit and other carnivorous cultures were not ketogenic.

      It’s unlikely that any wild obligate carnivorous animal is normally ketogenic in its fed state since most wild game is freshly killed and raw — and is therefore a source of pre-rigor glycogen — and most wild game is simply too lean to provide enough fat for an animal, and its family, to stay ketogenic — thereby providing sufficient carbohydrate-forming substance from the protein to keep them from being ketogenic. There is no doubt that animals prefer fatty pieces, but a preference for fat is not evidence of nutritional ketosis (we crave carbs too).

      Furthermore, anyone who has spent time in the outdoors knows that the key to survival is to eat energy positive foods. And that means starchy tubers, bulbs, corms, pollens, etc. Raw tiger nuts are extremely starchy, extremely nutritious, low in toxins, and have some RS2 in them. They are the perfect energy-positive staple. If they were cooked, they yielded even more calories (by converting the RS2 to digestible starch). If they were cooled, then they yielded a lot of RS3.

      But what most people don’t realize about tiger nuts is that they were a game changer for primates. They literally allowed an early human to obtain roughly 80% of their daily caloric needs with only 3 hours of foraging. That freed up an enormous amount of time to invent/create things — a practice that is rather unique and important to humans.

      So, in order for humans to continuously innovate their marvelous human technology, they didn’t just need energy positive staples. No, they needed extremely energy positive staples if they didn’t want to spend their entire lives foraging for food.

      But, when other kinds of tubers were eaten, I suspect cooking became a necessity to obtain those quick calories.

      (and if not, then that arguably ketosis was merely an evolutionary safeguard to survive starvation)?

      Yes. That’s my best guess. When you’re starving it probably helps to prioritize the most important organs — particularly the heart and brain (at the expense of peripheral organs/systems).

    • Bret on July 18, 2014 at 04:24

      Thanks for the perspective, Duck. That all seems to make good sense, and I am inclined to agree. The anecdotal tales of not-so-impressive long-term success with chronic nutritional ketosis corroborate these notions in my mind.

      Your point about us craving carbs is a good one, and paradoxical to the evolutionary argument of the LC/KG strategy. It makes no sense from that perspective for our bodies to crave poisonous substances.

      Finally, without a pathological condition beating people over the head with constant, painful motivational stimuli (like epilepsy), I don’t see how in the world anyone would think they can stick with such a dietary plan over an extended period of time, let alone an entire life. Admittedly, that is a different issue from what constitutes physiologically ideal food, but it is wholly relevant to the question of what is the right dietary recommendation for most people. I’m becoming ever more damn certain it ain’t chronic nutritional ketosis.

  20. Brad Baker on July 19, 2014 at 12:52

    My personal opinion is that a single meal per day (or loosely the “Warrior diet”) – any daily IF feed window of around 4 hours or less – is the most “paleo/ancestral” way one could eat. I think this is the most likely way that our ancestors ate and it seems to be an awesome way to eat to satiety or beyond (LOTS of food), both calories, and carbs, without counting kcals/grams or measuring ketones and blood glucose… while at the same time optimizing body composition – staying lean and retaining muscle. This has been my experience. Small breakfast of perhaps a few hundred calories of protein/fat, saving carbs for the feed window at night, does not seem to hurt things. the key may be not shutting down Glucagon during the day with carb consumption. So, yeah, not really a _real_ daily fast but pseudo-fast.

    Btw, a not uncommon body builder breakfast is meat+nuts. Makes sense to me for the same reason. Don’t shut down Glucagon and save the carbs for night time.

  21. Bret on July 20, 2014 at 22:24

    Fasting can be seductive, in that it can gradually adapt you to chronic under eating as you get used to it and plug into the euphoria it can induce. Chronic under eating comes with a whole host of problems, not the least of which is that your body gets very good at making you not exert much energy, all while it guards every molecule of energy it can keep.

    I am inclined to agree.

    This is one of the few differences I have with the Jaminets’ Perfect Health Diet recommendations. A daily fasting window sounds intuitively like a bad idea to me. (Granted, 16 hrs is a different kind of fast than what we’re talking about here, but it’s the idea of frequent imposed restriction that I find unwise.)

    Autophagic house cleaning sounds great, sure. And, it stands to reason that our paleolithic human ancestors had to deal with occasional scarcity or even starvation. But daily? Even weekly? I don’t buy it. That sort of frequency does not seem to be supported by modern observations of ‘uncivilized’ hunter-gatherers either.

    Seems to me that our best bet, when not purposely fasting (e.g.) once a month, is simply to eat when we are hungry, and stop eating when we are no longer. That strikes me as more biologically consistent than establishing and enforcing some arbitrary feeding window.

    • Bret on July 21, 2014 at 11:55

      @Bret, do you have any source for this comment?

      I don’t have references handy, but I am basing this off of what I have heard from Al Sears about his own observations of primitive peoples and from Sally Fallon about Weston Price’s similar observations. They go on a hunt every few days, but they don’t appear to restrict themselves from eating when they are hungry.

      Your comment inspired me to dig much deeper into the literature than I had previously. What I found is that almost all of the studies that are commonly linked in support of fasting recommendations are animal studies, mostly small rodents, mostly rats and mice.

      There’s some potential problems with comparing these small mammals to us relatively big humans.

      The Jaminets mentioned in Chapter 40 (“Fasting”) of Perfect Health Diet that a 24-hour fast in mice is equivalent to several days of fasting in humans. Then they go on to point out that human fasts lasting longer than 24 hours tend to result in greater susceptibility to infection, as autophagy is deeply suppressed upon refeeding and takes a long time to recover (vis-à-vis this study).

      They then go on to further support their fasting thesis, however, with references to positive effects from 24-hour fasts in rodent studies…which, by their own logic, would equate to at least three days in humans!

      The Jaminets do, however, point out in Chapter 40 several logical points I think worth consideration:

      Since the body consumes 500 to 600 glucose calories per day, liver glycogen stores become low about twelve to sixteen hours into a fast. This suggests that a sixteen-hour fast is sufficiently long to trigger autophagy.

      Long fasts do not upregulate autophagy more than short fasts do.

      We believe sixteen hours is the optimal length for fasts. This is short enough that it is possible to repeat the fast daily but long enough to induce elevated levels of autophagy.

      All things considered, I’m not too impressed with a daily 16-hr recommendation, for the reasons Richard mentioned in the original post and those that I mentioned in both this comment and the one previous. I think the risks outweigh the benefits of doing this stuff intentionally every day.

      However, I do have to give the Jaminets credit on a remark that I had forgotten about until I just now revisited the chapter:

      A fast should be terminated if it generates hunger or other signs of nutrient deprivation, such as dry mouth, dry eyes, irritability, anger, or anxiety.

      If I eat dinner at 7 p.m. and do not eat again until I am hungry the next day (for me, this is typically around 9 a.m.), that is 14 hours, right in the dead middle of the ‘benefits’ window they discussed way above. So I’m not trying to knock the idea. It probably doesn’t make a lot of sense to eat right before bed and then eat right after waking up. Certainly, the data seem to support the idea that constantly suppressing autophagy is not an ideal goal to shoot for.

      It just seems to me (based on my intuitive opinion, not documented data of rigorous science) that “Eat when you are hungry, and not when you aren’t” is more efficient advice than “aim for 16 hours.” But, admittedly, this is splitting hairs. 🙂

    • Brad Baker on July 21, 2014 at 13:54

      Keep in mind that these primitive people that Sears and Fallon talk about also move/exercise MUCH more than your average desk jockey today. If you happen to be an athlete or you actually do hunt/gather on a daily basis then, yeah, you can prob eat almost any frequency or amount you want to satiety. Desk jockey’s will tend to expand in girth eating whenever they are hungry, especially if that includes appreciable carbs at every meal/snack.
      Rat studies only show a cause and effect. Humans do not relate exactly and it’s not accurate to correlate a 24 hour rat fast to a 3 day human fast. One case in point is the rate of autophagy in fasting humans is higher at 24 hours than 36. Go figure. More human studies are needed.
      Increased longevity would be a nice side effect but I, personally, do pseudo-IF for the body composition benefits (mostly), time saving, and more daily energy it gives me. I don’t need studies to tell me it works, just a mirror.

      LeanGains >> top-ten-fasting-myths-debunked.

    • Brad Baker on July 21, 2014 at 07:11

      @Bret, do you have any source for this comment? … “That sort of frequency does not seem to be supported by modern observations of ‘uncivilized’ hunter-gatherers”.

      It seems logical to say simply eat when you are hungry, but hard to imagine how that took place in an era of no refrigerators, tupperware, and aluminum foil. Sun dried meats, nuts, fruit, and tubers? perhaps, but it’s by no means proven or even probably IMO.

    • Brad Baker on July 21, 2014 at 07:12

      oh, and also hard to imagine in the pre-agriculture era.

    • Bret on July 21, 2014 at 14:57

      Keep in mind that these primitive people that Sears and Fallon talk about also move/exercise MUCH more than your average desk jockey today. If you happen to be an athlete or you actually do hunt/gather on a daily basis then, yeah, you can prob eat almost any frequency or amount you want to satiety. Desk jockey’s will tend to expand in girth eating whenever they are hungry, especially if that includes appreciable carbs at every meal/snack.

      I’m not arguing fundamentally against any of those assertions. But they are largely irrelevant to my original statement. My concern is for whether a daily intermittent fast promotes ideal health, with all other things being equal. Carbs and activity levels are confounding variables in a discussion of fasting as a factor of good health. I’m not saying they’re irrelevant to the subject as a whole, but bringing in stuff like that leads a discussion like this down endless rabbit holes. If we are going to emphasize those variables, then we should probably also talk about alcohol consumption, indoor air toxicity from the air conditioner/kitchen appliances/etc, effects of cosmetic products on our metabolisms, inadequate sunlight exposure, the metabolic effects of staring at computer/TV/smartphone/tablet screens all day, and chronic daily stress–all of which the average modern westerner endures but paleolithic humans did not.

      I think the discussion will be much more sensible and useful if we frame it around the idea of what benefits we are likely to derive with all else equal.

      And I agree with what you said below–rat studies can stimulate human-related hypotheses, but cannot go all the way.

      Lastly, if IF works for you, that’s awesome. It is not my intent to discourage you from doing it. I am only saying that I myself am not inclined to stick to an arbitrary window of regular fasting, if it means repressing or ignoring hunger signals. Perhaps some future rigorous human subject data might change my mind.

    • Brad Baker on July 21, 2014 at 15:27

      I think you really have to at least try IF (become “fat adapted” as Sisson says) to understand completely… Just the definition of what (hunger) is to most people is skewed by a learned and IMO, improper habit/schedule of eating every 3 to 4 hours usually with carbs at every meal. My experience is eating more often, or eating carbs more often, or for breakfast makes me MORE hungry sooner rather than later. It’s counter intuitive that eating would make you more hungry, I know. I think Insulin, Glucagon (more so), lipolysis, etc. are the main factors. Keeping fat burning turned up. In short, once you get used to it, skipping one or two meals, or just have a very small breakfast of just a couple eggs, for example, is no problem at all.
      I don’t think exercise is a “confounder” in studying diet/nutrition if health and longevity is the goal. It is intimately related in MANY ways. Just one example of many… more muscle, more insulin sensitivity and glucose tolerance. I think it’s a big problem with many experts, Jaminet included, that they go into great details on diet while largely ignoring the exercise part of it.

      Btw, here is a recent article on IF that Martin posted about on Leangains – a friend of his I guess, who is a doctor and into lifting and IF. I haven’t finished reading it yet…

    • Brad Baker on July 21, 2014 at 15:39

      I think it’s perfectly logical to make the conclusion that if you are hungry your body is telling you that you should eat. It’s sending the signal that you should eat at this very moment, NOW. The thing is, is that assumption correct? Or, could it be that you body is warning you that you need to eat SOON…that you should get out of the cave, pick up that spear, and start hunting or gathering for something? In other words, the body is sending a signal that was adapted many thousands of years ago when you could not walk 5 meters to the fridge to satiate that hunger in a matter of minutes.
      I believe I read somewhere that many of the egyptian low class (workers) that built the pyramids ate once or twice a day with the major meal at night. Don’t remember where I read that.

      I’m not trying to convince you either. But I think more people should experiment with IF and see how it affects them.

      And… of course, lift!

    • Richard Nikoley on July 21, 2014 at 15:44

      Bret, I simply adore each and every one of your comments, and not only because you leave me with literally zero to add.

    • Brad Baker on July 21, 2014 at 15:50

      Interesting… it’s actually his doctoral thesis, on Intermittent Fasting.

      “The effects of intermittent fasting on human and animal health –

      a systematic review

      Thesis January 2012, University of Lund by Bojan Kostevski
      – See more at:

    • Brad Baker on July 21, 2014 at 15:54

      Rich, you’ll prob char my ass for saying this, but I think you also have a gaping hole in your blogging by focusing so much on diet and so little on exercise/fitness.

      Then again maybe you will cut me some slack since I used the words “ass” and “gaping hole” in the same sentence 😉

    • Bret on July 21, 2014 at 18:52

      I think you really have to at least try IF (become “fat adapted” as Sisson says) to understand completely… Just the definition of what (hunger) is to most people is skewed by a learned and IMO, improper habit/schedule of eating every 3 to 4 hours usually with carbs at every meal. My experience is eating more often, or eating carbs more often, or for breakfast makes me MORE hungry sooner rather than later. It’s counter intuitive that eating would make you more hungry, I know. I think Insulin, Glucagon (more so), lipolysis, etc. are the main factors. Keeping fat burning turned up. In short, once you get used to it, skipping one or two meals, or just have a very small breakfast of just a couple eggs, for example, is no problem at all.

      Different people have different experiences. I have been what Mark would call fat adapted for quite some time now, ever since April 2012. That doesn’t mean I never get hungry for breakfast sooner than 16 hrs after dinner. There are enough times when I skip meals due to my schedule (and am fine in those cases–I don’t feel ravenous, obsess over food, or start gnawing on my arm), that I opt not to do it daily and on purpose.

      We’ll agree to disagree over whether exercise is a confounding variable. I’m not convinced by your argument that it is any more relevant or pertinent than any of the other hypothetical variables I mentioned.

    • Richard Nikoley on July 22, 2014 at 05:04


      Take a hike. 🙂

  22. Brad Baker on July 21, 2014 at 07:19

    I agree that daily fasting *IS* non-intuitive, at the same time is quite effective and a GOOD idea for many people (dunno if you can say *ALL*). The fact that you can build muscle while eating this way, I think is evidence that it IS beneficial. The body will not build muscle if you are eating below maintenance levels in calories/nutrients.

  23. Jon McRae on July 31, 2014 at 14:06

    I am starting a 30 hr fast will report how I feel tomorrow, I started at noon today 7/31/2014 and will right after 6pm on 8/1/2014, i am looking forward to the mental clarity that some people reported and the sensation of fullness after the 24 hour mark, any supplements that I should take with the water that I will be drinking?

    • LaFrite on July 31, 2014 at 21:45

      “any supplements that I should take with the water that I will be drinking?”

      yeah, coffee 😀

    • LaFrite on July 31, 2014 at 21:46

      I should add: I do 40 to 48h fast every week and I never supplement. I would do it though for longer ones.

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