Fasting triggers stem cell regeneration

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Fasting triggers stem cell regeneration

This topic contains 22 replies, has 6 voices, and was last updated by  dykask 6 years, 7 months ago.

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  • Here’s an article I just came across on stem cells and fasting. It claims “prolonged fasting” — two to four days of no food — induces immune system regeneration.

    This is an incredible article!

    May be the inspiration I need to do some longer fasts…..I’m working up to it


    this thread touches upon something I am thinking about… I am now into my 6th year of periodic fasting. In practice, I went on 5:2 for 1 year between 2012 and 2013 and then swapped to 6:1 which I have since then done. I am 71 kg (and have stayed that way +/-1kg since 2013, more or less!) and 182cm, run three times a week. So I do not want to lose more weight. My only slight concern is that my cholesterol level has been a challenge. It was excellent during 5:2 (like 4.6 with anything below 5.2 being good and healthy) and with 6:1, it has mainly been right at 5.2 with things like blood sugar being excellent, just like blood pressure and other elements. Long story short, I am not doing this for any further weight loss but to preserve the low IGF1 level (around 120 now on 6:1; I am a man 39 years of age) and the healthy weight.

    BUT – and this is where I am getting confused. In terms of regenerating stem cells, it seems my “solution” – essentially one meal of 600-800 calories – over a period of roughly 36h – is useless? Is it the case that you need to fast for like 2 days to really make a difference? I also do skip meals several times a week; in my case it is the breakfast as it is by far the easiest. So I have like two occasions per week with an eating window of like 8-9h but I do eat the right amount of calories for a day. I am not losing weight and I have done this for five years now and am feeling great, having no mineral or vitamin deficiencies, so it definitely does not harm me (well, let us see in 20 years 🙂

    Reality is that when I check the latest videos on the topic, a lot has changed and been redefined since 2012 when I stumbled across “Eat, fast and live longer”. I have no chance of following all the latest but do occasionally check what Mr Mosley and Mr Longo have done lately etc. You who possibly joined later than me, do you think my strategy is all wrong? Going back to 5:2 is not really an alternative for me, but 6:1 works beautifully for me and clearly has some positive impacts. Still, I am wondering if I am throwing time and efforts away with this strategy, or could substantially optimise it, of having one fasting period of 36 hours with one meal (it is like 24h fasting + 12h fasting after that meal).

    This stem cell discussion is extremely interesting, but I am wondering if I have now got it all wrong with this one fasting day as it sounds at a first glance that my approach does not trigger it. So, perhaps this approach is just not working at all, and the low IGF1 is not indicative of cell regeneration/protection.

    Any thoughts about this?


    Best regards, Tobias

    You might try sending your question to Dr. Jason Fung or Megan Ramos whose Intensive Dietary Management blog contains a great deal of good information about the variety of intermittent fasting schemes that people try. Fung is a nephrologist located in Toronto whose many patients include those who’ve reversed their type 2 diabetes, and he is keenly interested in the data that demonstrates how people’s health is improved beyond their concern with weight.

    Thanks a lot, Jifty! I really rarely visit this forum (which is a shame) – do you have their contact details or official forums?

    Tobias, I personally think 36 hour fasts at best have only mild impact stem cell regeneration. Most sources point to more like a 72 hour water fast, but there are variations all over the place. Right now I’m trying to do a longer fast one or twice a year. No idea if that is really enough or not, but that is all I can handle right now.

    Got it, Dykask – thanks for your response and I think you are right. On the other hand, I also see my limitations, just like you. I am fortunately not really in a need for stem cell generation – I am more keen to know that what I am doing does have a positive and meaningful impact. I will try to figure out. Clearly, what I do does lower IGF1 levels significantly and this regime (like 600-800 calories as one meal within 36h) has an impact, and I combine this with several minor interventions during the week, like skipping breakfasts on the days I am not running. If I exercise, I really do not dare not eat right after it; that does not seem healthy. I just came under the impression that lower IGF1 is just a part of the puzzle and that the other parameter is really time, i.e. that the lower IGF1 level itself does not lead anywhere if it is not combined with a longer fasting, of minimum two days.

    Reality is, I just do not see myself doing that. One day per week works fantastically well for me and is a piece of cake in comparison with 5:2 for me. Also, skipping a meal here and there is a non-issue, so hopefully I have a regime that works for me. I just want to figure out if it is really effective and has a meaningful impact.

    I think there is an element of “placebo” to some extent, but I really think that my short-time memory has immensely improved under this scheme, so I think the benefit is there. Clearly, my physiology resembles that of a lean muscle mass that they talk about, it is excellent for weight maintenance and IGF1 levels and my cholesterol level that was always a bit too high despite not being overweight are kept in check – so it is worth it anyway! I am just trying to figure out if I can adjust the scheme to make it more optimal.

    Dykask, from what I understand from Valter Longo in a recent video available on Youtube, a longer fasting (5 days, I think) had a positive impact for like 6 months in the case of MS patients, which is nothing short of remarkable. Obviously there the case is about knocking out the “sick” immune system cells which cause the auto-immune disease and replace them with healthy ones. So if you do it like twice per year, it really does sound as though you will have substantial health benefits from it. Good luck with your fasting!

    I think I found it – thanks for mentioning Jason Fung! I am all happy now 🙂 – this suggests that autophagy (I learnt a new word today :)) does occur during the course of 16-24h of fasting. Thanks for the help!


    I’ve been 5:2 for just over four years, losing 102# in the process, and also reversing my absolutely horrid blood chemistry, which is now properly balanced between HDL, LDL, Triglycerides and fasting blood sugar … Top that off with a return to normal blood pressure without medicine, and you can say I have benefited greatly from this lifestyle …

    5:2 IF has essentially saved my life, and I am so thankful for that documentary by Dr. Mosley … I believe I would have never been able to restore my health in any better way.

    I have also been fascinated by the new science regarding fasting and cellular regeneration … The balance between Insulin and Glucagon, the Autophagy process, (and Mitophagy as applied to Mitochondria specific cells) …

    These are all new terms to me, but I can now see that intermittent fasting does in fact stimulate stem cell activity, and not just those that reproduce immune cells, but that the same repair process affects all stem cells, which means that all tissues experience higher cellular repair activities when in the fasting state.

    The story about the three day fast that stimulates complete immune system regeneration was also published by The Telegraph in 2014 (I just found it recently – …

    While it might be true that a 72 hour fast restores 100% of the immune system, I do believe that shorter fasts also engage in the same process, and still have beneficial, regenerative effects, but simply to a lesser degree …

    In other words, that a 24 hour fast would regenerate 33% of the immune system, not 100% as in the 72 hour fast. I believe that it’s the fact that the body is in the fasted state, with low Insulin and high Glucagon levels present in the blood stream … That once the body is in the fasted state, it begins to accelerate cellular regeneration, through low level autophagic/mitophagic activity, and that it simply takes three days of that activity to restore 100% of immune cells … Two days would restore 66%, one day would restore 33%, etc …

    Taking that one step further – 12 hours in a fasted state would restore 16.5% … 6 hours = 8.25%, etc … So, I believe that being in the fasted state, with low blood sugar, low Insulin and high Glucagon, allows for that low level process to start, and that the number of cells involved increase in correlation to the amount of time in the fasted state …

    In short, once cellular regeneration begins, it works slowly but inexorably, cell by cell, using autophagic/mitophagic rebuilding processes. 72 hours gets you 100% immune system regeneration, and 48 hours gets you 66%, etc.

    If you accumulate 72 hours total time in the fasted state, you will regenerate 100% of the body’s immune cells, whether in one long fast or in several shorter fasts.

    Furthermore, I an seeing scientific studies that show this regenerative activity is not limited to immune cells, but to EVERY tissue …

    Autophagy affects all tissues, as part of the body’s overall homeostatic control system … It is an autonomous biological process that only occurs in the absence of insulin in the blood stream. When it occurs, it occurs in every tissue, not just immune cells … There is no reason to believe that this critical stem cell process is limited to one type of stem cell. Stem cells control most all of the cells of your body tissues, and the mechanisms at the cellular level are the same for each type.

    I have more stuff to share with this group – it’s a fascinating subject area to me, and, just hitting sixty years old, it’s the reason I will continue to fast after I reach my ideal weight.

    More coming …

    The reason I speak of Glucagon, Insulin, and how they relate to Autophagy:

    This is an excerpt from a study named, “Hepatic Autophagy Is Suppressed in the Presence of Insulin Resistance and Hyperinsulinemia”

    “2). Autophagy is normally activated by glucagon or deprivation
    of amino acids during starvation (1) but inhibited by amino
    acids and/or insulin through the mTOR- or/and Akt-dependent
    pathways after food intake.”

    The point being, Autophagy is suppressed in the presence of insulin.

    Reading the rest of this article, it implies that those individuals who are experiencing insulin resistance experience reduced levels of autophagic activity. Being that most persons experiencing insulin resistance, which is a symptom of the dreaded Metabolic Syndrome, most persons with that condition are obese, or morbidly obese, as I was.

    When I think of the typical modern American diet, with all the excess calories, with numerous meals most all day, even midnight snacks before bed time … There is hardly any moment where a person has a chance to completely digest ALL food in time to experience autophagy. I would eat breakfast before my ‘midnight snack’ from the previous night was fully digested – Perpetual Fed State = Perpetually suppressed autophagy …

    I think I might have been in a ‘Fed State’ for about 30 years straight … No wonder I was so sickly … No wonder half of society is so sickly …

    This is amazing stuff …

    And this is why I mention that ALL stem cell types are affected or stimulated through fasting, just as those that produce immune cells are induced to produce …

    This article is titled, “Autophagy in Stem Cells”:

    (It’s a challenging read for a non-microbiologist …)

    “Autophagy is a highly conserved cellular process by which cytoplasmic components are sequestered in autophagosomes and delivered to lysosomes for degradation. As a major intracellular degradation and recycling pathway, autophagy is crucial for maintaining cellular homeostasis as well as remodeling during normal development, and dysfunctions in autophagy have been associated with a variety of pathologies including cancer, inflammatory bowel disease and neurodegenerative disease. Stem cells are unique in their ability to self-renew and differentiate into various cells in the body, which are important in development, tissue renewal and a range of disease processes. Therefore, it is predicted that autophagy would be crucial for the quality control mechanisms and maintenance of cellular homeostasis in various stem cells given their relatively long life in the organisms”

    This implies that autophagic activities affect other stem cell types using a more or less universal process that affects each type in a similar manner, which is to stimulate repair of degraded cellular material, including tissue cells and mitochondria (which provide energy to your cells) …


    it is an amazing story that you shared – well done and it is really pleasing to hear how natural interventions can make such a difference! What you say does seem to imply that even a shorter fasting regime has positive impacts. I was not overweight when I started off on this regime; I just had some 5 very unnecessary kilos around my waist that I just got fed up with. Once I got rid of them, I really did not want to go back to where I was and I saw the positive impact on my cholesterol level and my physiology just changed completely and I got much leaner. Running got much easier. At the same time, I see in my case that it is important to strike a balance – being around 70kg and 1.82m, and running three times per week at quite a high pace, it is certainly not about losing more weight but I also need to think about getting enough nutrients into my body and not embark on any extreme journey. I could not see myself doing 2 days of fasting a week under these circumstances just to push for some extra stem cell regeneration, to put it simply. But it sounds as though there is a value in doing what I currently do, so many thanks for your input and for sharing your amazing story!

    Rgds, Tobias

    Hello Tobias,

    Before I saw Dr. Mosley’s landmark documentary, Eat, Fast and Live Longer, I was 115# overweight, with a BMI of 42, too much bad cholesterol, too little good cholesterol, triglyceride levels that suddenly jumped from the 60’s to above 400!

    I was miserable … I was desperate … I needed to do something to save my life … Before I saw that documentary, I was nearly hopeless …

    I actually started following the Esselstyn diet at first, but there was no provision for weight loss in that diet – it’s main purpose was to reverse heart disease (a worthy goal), and I was able to change my approach in meal preparation, and focus on veggies, whole grains and fruits as regular staples …

    I felt better, yes, but I wasn’t losing any weight, which was a critical aspect of my situation …

    Watching the documentary opened my eyes to the benefits of fasting, and I could then understand that, through fasting, I would not only lose fat weight, but that my blood chemistry would improve as well …it’s exactly what I needed to resolve my set of symptoms.

    I started in earnest, and within two months I had lost about 40# … There is nothing more inspiring than success … It took about two years total to lose 90% of my excess weight, and I’ve spent the last two years chipping away at the remaining ten percent while also starting a muscle development/strength training program – when the fat disappeared from my arms and legs, I realized my skeletal muscles had atrophied severely – this is what happens when you are lazy for decades in end … My arms were all fat with little lean muscle mass. When the fat was gone, I had puny muscles and bone … Since muscle tissues are a primary user of caloric intake, it became very important to rebuild my musculature, and restore a normal metabolism (more muscle mass = higher metabolism)

    Now, as I look at the end game and ask myself how I intend to play out the final steps as I approach my target weight (6# to go), I’ve begun to dig deeper into the health benefits of fasting, and that’s what brought me here …

    I’m learning slowly, but I’m pretty sure I will be fasting the rest of my life …

    I’m not so sure that fasting for 24 hours would be enough to give a 33% rejuvenation of the immune system. Things in the human body are seldom linear.

    After we stop eating:
    * First it takes hours to finish processing the food we have just consumed.
    * Second the liver releases glycogen until it runs out and that takes most of a day, so metabolism hasn’t been too impacted by the fasting yet.
    * Over time there is more stress to acquire fuel for the body and some other processes kick in more and more.

    Personally I have noticed a shift of sorts that tends to happen around 20 to 24 hours. Typically I’ll experience a dip in blood glucose and maybe even feel light headed for a while and then blood glucose will go back up. Also I know from experience I only have trace amounts of ketones at the 36 hour mark, but much higher levels at the 60 hour mark, maybe about 50% of what I obtained by day 4 when I did fast for a week.

    I think there is probably a lot of value is the last 12 hours of the 36 hour fast, but it probably results in a lot less than what a linear response would be.

    Also just to be clear, just because one can’t measure ketones doesn’t mean that there isn’t some use of fat going on, there is always some fat be broken down in the body. When we are fasting there clearly isn’t much fat being stored either. I think 36 hour fast are good for using some fat, they also probably help a great deal with better hormone levels. Past that the impacts are probably quite limited as compared to longer fasts.


    it is really quite an achievement! Well done. It appears you did not really hit any plateau, did you? Which in itself also would be an interesting thing as it seems to impact many people on any diet, including this one. What I have noted is that at least my body needs a shock to the system once in a while for things to move. It is more of self-experimenting, I guess, so should be done with a great deal of care, but when I was diagnosed with gluten intolerance, for instance, and I had to change my diet (like bread out, more nuts in) my weight dropped dramatically. But then it caught up again (which was good as I was rather 68 than 70 kg at some point which was just too low for me to feel comfortable with). I am trying some minor changes alongside my rather intense training sessions and this seems to have very quickly impacted my body fat. I suspect though that my body will accommodate at some point. Conversely, when for a month I could not run at all but kept my diet regime and everything else I do, my bloods were not that good. I am now back in the good old regime again, so I really hope that those bloods were just a “blip” on the radar. I am just relating to what you say about lean muscles – I think you need to find new triggers from time to time to expose your body to (within limits, of course) challenges it needs to cope with. Building muscles to impact the amount of calories your body needs to burn to stay functioning is one of them, I guess.

    Good morning,

    I completely agree that natural processes are rarely linear – more likely there is a slow curve involved as a process ramps up, and lingers as the process completes …

    Also, when I speak of time frames, I speak of when all digestion completes, some hours after a last meal, when blood glucose finally drops, and insulin drops (and Glucagon rises) in response … We aren’t in the ‘fasted state’ until then …

    I think my point is: One needn’t go the full 72 hour route, and that one could benefit from shorter fasts, but just to a smaller degree.

    Those of us focused on the long term, as I am, will still eventually restore that immune system, but in due time …

    This is a fascinating subject area … I love this stuff …

    Hello Tobias,

    I absolutely hit plateaus … Over four years, it’s been nothing but up and down …

    As with others, there are times when I would awaken after a good fast day, and find I’ve lost nothing … Other times, I would drop a bunch … I think that weight loss using 5:2 is a cumulative process, and that the body resists at times, for reasons I don’t understand …

    Also, one of the great aspects of 5:2 Intermittent Fasting is the flexibility … I will usually stop fasting during holidays … In the U.S., we have our Thanksgiving holiday, followed a month later by the Christmas holiday. I decided early on to just go enjoy those moments with friends and family, and not worry about my weight … Life needs to be enjoyed …

    I have gained up to twelve pounds during holiday, and spent the next month stripping it back off … It’s a bit counter productive, yes, but it’s great that we can still share those moments with those we love, and celebrate without worry …

    It’s been a long journey for me, with lots of ups and downs, but it’s been mostly down …

    My two main mantras:

    1) I can eat that tomorrow

    2) Just keep doing it, and you will get there …

    Have an awesome day, folks … I get to eat this morning!

    Back on the topic …

    I agree that one doesn’t have to fast a full 72 hours to see benefits. I just think that in a 24 hour fast or even 36 hour fast autophagy is much of a factor.

    The first 24 hours the body is just moving into the fasted state, so likely almost no autophagy occurs. However one would see drops in Insulin and IFG. There should also be increases in HGH and Glucagon. That sets the body up for more lipolysis and improving insulin sensitivity.

    Past the first 24 hours, autophagy likely starts as the body has stress to produce enough glucose for the body as typically there isn’t enough ketones for fuel.

    I have to wonder if being in ketosis would actually work against autophagy?

    Hi Dykask/TrajanGregory,

    many thanks for sharing and sorry if I drifted off topic. You really seem to know the details very well, which is pleasing and I learn a lot from what you write. What I noted on my current regime (one meal over the course of about 36h, coming in at around 800 kcal) is as you say that it does have a significant impact on IGF. In combination with at least two days a week of skipping breakfast – giving me pretty much 18h, including sleep, of not eating and then an 8h “eating window” – my IGF is about 120, with the normal range being between 100 and 240. During days when I exercise and the weekend, I eat normally, meaning 3-4 meals on those days but still sticking more or less to the recommended daily calorie intact. That is what I achieved on 5:2 as well and I find this 6:1 regime (+ some skipped meals) so much easier to manage, especially since I do do quite a lot of exercising as well and am normal weight, so I do not want to push things to extremes. Now, from what you say, I suspect that what I do at the best has a moderate impact on stem cell regeneration. Given that I eat once after 24h – without I just cannot sleep, I have noted – I suspect that the whole cycle is broken at that time although the impact on IGF1 is tangible and definitely there. Definitely fat is burnt during these 36h cycles; it is visible. I guess that the question is whether it is actually worthwhile skipping the weekly routine and instead have some kind of monthly, but much tougher schedule. Or change of one of those weekly routines into a tougher, monthly no-food-at-all 36h… So “food for thought”, if I can use the expression here 😉

    Just like TrajanGregory, I enjoy life when I am away on vacations etc. I have found that there is no issue with going back to the regime afterwards and I actually look forward to it – just as much as it is immensely enjoyable to eat the day after a fasting day! I think that is the “secret” in my case, and probably for many others, and why I just go on doing it. I have felt the same motivation for five years now so hopefully this will be a life-long thing.

    … and just like Gregory, I stumbled across “Eat, fast and live longer” and it just changed my understanding of how I live my life…

    @tobias – I mostly just do water fasts for 36h, although I’ve done some 60+ hours fasts, one was 80+ and the longest one was one week.

    I don’t eat because once I start eating I become hungry, when I don’t eat hunger might happen but typically it lasts less than 1/2 hour. I do drink black coffee or straight tea. Sometimes I’ll chew some sugarless gum, or use a sugarless mint for my breath. A few times when I was feeling off I did consume a bowl of miso soup which is less than 30 calories or suck on a small piece of salted plum which is only a few calories. That is pretty much it.

    We are all different so I realize that some people feel better eating a small amount, I’m just not in that group. However I’ve noticed that over time, the fasting has become much easier than it used to be. Sometimes I don’t even notice it, at least the typical 36h fasts I do. I often also try to do a hard workout before breaking my fast.

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