Fasting (Detoxification and Glycogen replenishing) (1 Viewer)

[Ockeghem]

Sam,
I think you and I will need to disagree with regard to this. I am not trying to convince you to fast. The reason I created the thread was to share my fasting experiences. You may of course believe what you wish, and you may dismiss my own empirical evidence (about four years worth of regular fasting) if you wish.

And yes, I have had blood work done recently -- both during a fast and not during a fast. I have no medical concerns whatsoever. Of course there was little or no glucose and glycogen stores, but this is one of the main reasons that I fast. And my overall positive results probably have something to do with the amount of fasting and running that I do.

 

[Stan]

I'm sorry Scott but that sounds completely ridiculous and unhealthy.

Scott, commented earlier about dropping a tremendous amount of weight due to illness.

I still find myself with almost no appetite and have to force myself to eat quite often.

I've injured myself many times (broken ribs, many lacerations to my head and chin, actually have had almost every repair possible, glue, stitches, staples, bandages, etc.) due to passing out from low blood glucose and low blood pressure if I don't eat.

Do you experience symptoms like that at all? And if you're not eating, what's your body using for fuel. I can see going a few days without food, but 42? You're basically using your own body as fuel to keep it running. Do you get blood tests for potassium, sodium, etc.? Eventually you're flushing these out of your body which could be very dangerous since they are what keep your muscles working, particularly your heart.

 

[Ockeghem]

Scott, commented earlier about dropping a tremendous amount of weight due to illness.

I still find myself with almost no appetite and have to force myself to eat quite often.

I've injured myself many times (broken ribs, many lacerations to my head and chin, actually have had almost every repair possible, glue, stitches, staples, bandages, etc.) due to passing out from low blood glucose and low blood pressure if I don't eat.

Do you experience symptoms like that at all? And if you're not eating, what's your body using for fuel. I can see going a few days without food, but 42? You're basically using your own body as fuel to keep it running. Do you get blood tests for potassium, sodium, etc.? Eventually you're flushing these out of your body which could be very dangerous since they are what keep your muscles working, particularly your heart.

Stan,

Yes, I remember our prior conversation. I feel none of the symptoms that are in some of the links posted by Sam above or what you have experienced in your post above, but that's not that unusual, since I have a solid fasting base upon which I have worked my way up to with regard to the length (and frequency) of fasts that I do. It's similar to the amount of running mileage that I do. I didn't just decide the first day I ran that I was going to run thirty-five miles. It took me years of intense training and resiliency to build up to the amount of mileage I can now accomplish.

"You're basically using your own body as fuel to keep it running."

Precisely. Fat is burning away, and that's a very good thing. And loss of muscle mass, which one doctor I speak to helps me to gauge on a regular basis, does not occur until one has fasted far beyond the point at which I decided to break my most recent fast. And incidentally, I may not be as lean as some people may think. I have weight to lose, as maintaining my 'ideal' running weight takes work. I track my BMI, my blood pressure, my HDLs and LDLs, my triglycerides, and other factors that are important to runners.

The body uses keytones as the back-up fuel system. These have the ability to keep the vital organs going for several weeks. One of my friends who is a doctor explained to me how they are able to cross the blood-brain barrier, which I find fascinating. Keytones are what maintains our heart and brain. Interestingly, when I was about three weeks into a fast (not this past one, but a prior fast), I ran for about ten miles (in day twenty-one) while I was still fasting. It was similar to 'burning the candle at both ends,' so to speak, and I learned a great deal about what keytones are designed for, and what they can and cannot handle when put under a fair amount of stress.

My nutrients are fine, because our bodies have enough nutrients stored away in cells to sustain a body for many weeks. (I am of course speaking of a normally healthy person.) Another of the doctors I speak to regularly says that when a faster takes a supplement, they run the risk of upsetting the natural balance that is already there. Of course, if I were to fast for longer than I did recently (which I don't have any intention of doing), I suppose that they would eventually have to become depleted (similar to how the glucose and glycogen are depleted, except that those are exhausted early on). As a runner, the glucose - glycogen aspect of fasting is to me fascinating, hence the title of this thread.

 

[Sam Posten]

Precisely. Fat is burning away, and that's a very good thing. And loss of muscle mass, which one doctor I speak to helps me to gauge on a regular basis, does not occur until one has fasted far beyond the point at which I decided to break my most recent fast....My nutrients are fine, because our bodies have enough nutrients stored away in cells to sustain a body for many weeks.

This is the essence of what I dispute. You can take all the vitamins you want but if you are performing normal daily activity you are eating away at muscle and organs to fuel the work you are performing.

 

[Ockeghem]

Sam,First, I don't take vitamins. And secondly, what you say is simply not true, unless one were to enter into the starvation mode (a very dangerous place to be, and not somewhere I will ever allow myself to go). It's also not true if you are performing rigorous (as opposed to normal) activity. The body will burn much of its fat first. And I know, because I lose about 1.15 lbs. per day (on average) during a several-week fast. And I have done this for four years, and I am fine. Please research keytones, the fuel source that comes into play once glucose and glycogen are depleted. They are a marvel unto themselves. If you continue to choose to dispute various claims I have made, then that will have to do.

 

[Sam Posten]

If you can produce any scientific research about it I'd be happy to. Sadly all that seems to be available is stuff from people who are pushing such a diet most of whom are trying to sell you something.

 

[Ockeghem]

Sam,
I don't disagree at all that there is a load of rubbish out there from those whom are trying to sell you something. One of the doctors I speak to frequently says that the pharmaceutical industry is one of the greatest culprits in this regard.

Your point about muscles and organs is one of the first things I addressed back in late 2008 when I began fasting. My friend (a medical doctor whom I see every week) said that muscle mass could become a concern unless you have much fat to lose, in which case the body, lacking food, will (in conjunction with keytones) use a large majority of that up first as fuel. (And he turned out to be right. I lost 112 lbs. in twenty months through proper eating, fasting, and exercising. And while fasting, I did not lose any muscle mass.)I went forty-two days without an ounce of food, and I embraced the fast (and the keytones) very nicely. It was one of the easier fasts I have completed, no doubt aided by the fact that I had to that point done so many prior fasts, just none that had gone on for quite that long (although in retrospect, it was only about eighteen days longer than my previous longest fast). I also fasted 132/365 days last year, a mark I will eclipse in about another month or two for 2013.

Take a peek at some online or print resources that discuss keytones. Since you provided several links rather quickly in a prior post, I doubt you need my help retrieving some useful and interesting links on that particular topic. Keytones really are an amazing phenomenon. I will also ask one of my friends (a doctor) to consider visiting this site, as he will no doubt have many articles that address some of the concerns and other topics that you and others have raised.

 

[Stan]

Scott, not sure how to state this politely, but were you very overweight at one time?

Does your body now cycle through being incredibly fit and in shape, then overweight, then you fast and lose it all, just to start the cycle again?

Don't mean this to sound rude, just curious.

 

[Ockeghem]

Scott, not sure how to state this politely, but were you very overweight at one time?

Does your body now cycle through being incredibly fit and in shape, then overweight, then you fast and lose it all, just to start the cycle again?

Don't mean this to sound rude, just curious.

Stan,You stated it just fine! For about twenty years, I was at a wonderful weight, and I stayed there because I was younger (higher metabolism), ran two or three marathons-per-year, and while training for marathons, ran enough mileage-per-week which kept me at an ideal running weight. Then, I went to graduate school, earning two master's degrees and a Ph.D. During that time, I did very little physical activity (due to a lack of time), and I ate whatever and whenever I wanted (a horrible decision, by the way). About five years ago, I stepped on the scale, and yes -- I was overweight. Then I cut down to one meal-per-day and lost the weight I mentioned above. (Incidentally, the math comes out to less than a 1.25 lbs. lost per week over a twenty-month period of time.)

My body weight during my fasting adventure (roughly the past four-plus years) during a typical year is maintained at two weights. The first is my ideal running weight, and the second is my ideal non-running weight. If you were to see me on the street, you would say that I look fine, but in my heart I know that being 185-190 lbs. (an okay weight for a person my height who does not run) is not the same as being 155-160 lbs. (my ideal running weight). I have vacillated between this twenty-five or thirty pound window throughout the course of each of the past five years. So to answer your second question, I am never overweight any longer, although I always have some weight to lose as I am not at my ideal running weight all of the time. Intermittent fasting is what helps me to maintain a tighter window, and this routine took me at least a year to fine-tune to get it to where it is now. And I continue to try different methods (hearkening back to the 3:4, 4:3. 5:2, and 6:1 methods I mentioned about a page or so ago) in order to find the first best regimen -- assuming that there is only one -- for myself.

 

[Sam Posten]

I see no legitimate links from reputable sources on the subject so lets see what you've got.

Let's put it this way, if what you are saying is correct the medical community should have tons of interest in it and the DOD would be beating down doors to embrace it.

Like I said, I don't doubt you've got a ton of links you can point me to, what I doubt is that there are serious long term studies of both the positive and potentially detrimental effects of long term fasting.

And there's an awful lot of hucksters instead.

In a 15 second google search I came up with the American Cancer Society, NIH and Mayo Clinic all listing the very serious side effects of so called detoxification and not a single rah rah from anyone that wasn't a rogue element. If you can bring such documentation it would be very eye opening.

 

[DaveF]

I went forty-two days without an ounce of food, and I embraced the fast (and the keytones) very nicely. It was one of the easier fasts I have completed, no doubt aided by the fact that I had to that point done so many prior fasts, just none that had gone on for quite that long (although in retrospect, it was only about eighteen days longer than my previous longest fast). I also fasted 132/365 days last year, a mark I will eclipse in about another month or two for 2013.

No food = no calories? Or no solid foods, but you're drinking sugars? Simply put, are you starving yourself for weeks at a time?I'm still baffled by the whole thing.I've done short term fasts, 12-24 hours. I get the spiritual motivations. But practically, food deprivation is like sleep deprivation for me. It diminishes my ability to think and function professionally and personally.

 

[Ockeghem]

I am writing this of my own accord. In other words, I have not been reminded to do it. I am not attempting to convince anyone to fast. I am just sharing my experiences based on my own empirical evidence gleaned from years of fasting. Fasting ought not to be attempted without first consulting with your physician.

No food = no calories? Or no sold foods, but you're drinking sugars? Simply put, are you starving yourself for weeks at a time?I'm still baffled by the whole thing.I've done short term fasts, 12-24 hours. I get the spiritual motivations. But practically, food deprivation is like sleep deprivation for me. It diminishes my ability to think and function professionally and personally.

Dave,Correct (no food and no calories). I don't ingest drinks with sugars whether I am fasting or not. Am I starving myself? No, I'm fasting. I have never met anyone who is actually starving. When people say that they are starving, I believe that they are incorrect. What they really mean to say is that they are hungry. Starvation mode occurs much later than any fast I have ever undertaken. That is something (as I mentioned above) that I would never allow myself to do, as quite honestly that is dangerous territory. When you fast, you will become acutely aware of various 'triggers' during the fast. In other words, you will know when to continue and when to stop. This recent fast was about my fourth attempt to reach forty days. During the other times, I knew it was time to stop short of that, so I stopped. In other words, my biofeedback trumped my desire to reach a goal as far as length of fast is concerned. It's really not rocket science.

As I have said more than once, every fast I have undertaken -- be it a three-day, one-week, two-week, three-week, or forty-plus days fast, has been done responsibly. If during any fast I have ever felt anything out of the ordinary (and I have a few times), then I have stopped the fast. To reiterate, biofeedback always ought to take precedence over a predetermined amount of time to fast. In my four-plus years of fasting, I have become aware of various signals ('feedback,' if you will) and I know when I ought to fast and when I ought not to fast. One of the doctors with whom I correspond frequently reminds me that biofeedback trumps theory.

I can't go without sleep for very long, and frankly I wouldn't even try that. When I was eighteen or nineteen years old, I once went seventy-two hours (I had my reasons at the time) without sleep, and that is something that I will never do again. I also don't believe in dry fasting, although I belong to Boards on which several members seem to enjoy the benefits of that as well as water fasting.

Truth be told, the first three days of any no-food fast are the most difficult for first-time fasters. After that, the hunger disappears, and your mental clarity is heightened markedly. I attribute this to more oxygen being routed to the brain, although that is speculation on my part. It may be in part because the body does not have to work virtually every minute of every day digesting food (a physiological process that seems to take a large amount of energy for our bodies to accomplish). I do like the lower metabolic rate (this is actually one of the reasons I began running back in the 1970s -- more on this later if you wish) when one gives their digestive system a rest. A lower metabolism is something one can 'feel' -- especially for someone like myself who over the past thirty-five years has become very attuned to his body (e.g., active and resting pulse, blood pressure, and various other cardio-related aspects including atrial fibrillation and ventricular tachycardia). Some of the evidence seems to suggest that a lower metabolism may equate to a longer life span, and this is very intriguing to me.

Another benefit of fasting that I experienced during my last fast was how my wife and four of my children were sick at various stages of the fast, and yet I felt wonderful the entire time -- no cold, no headaches, no nothing. To me this makes sense since the immune system is strengthened when it isn't being asked to 'fight a war on two fronts,' so to speak. I have wondered for years why I am never hungry when I am sick. It may be because the body is telling me that food isn't the answer; rather, curing whatever ills reside in the body is paramount, and the immune system needs to concentrate on this first and foremost rather than on ingesting and digesting sustenance.

 

[Mike Frezon]

Scott:

Once a fast is over--especially one of this duration--how do you reincorporate food into your system?

Is it a slow reintroduction? Or do you sit down to a big breakfast of bacon & eggs and waffles and french toast and pancakes...?!?

 

[Ockeghem]

Scott:

Once a fast is over--especially one of this duration--how do you reincorporate food into your system?

Is it a slow reintroduction? Or do you sit down to a big breakfast of bacon & eggs and waffles and french toast and pancakes...?!?

Mike,
You ask a very important question. In fact, I was curious if this would eventually come up. Much of what I have read over the years on the subject asserts that how one breaks the fast is more important than the actual fast itself. This is one area in fasting that I still have to work on dilligently each time I break a fast. During a fast, you think about various foods a lot, but the desire to eat them is absent. And sometimes your mind can be thinking about all of the wonderful flavors that are awaiting you once you have met your goal. And believe me when I tell you that when you have not used your taste buds for weeks, all flavors are more pungent and the sense of taste is noticeably heightened and/or more acute.

Once the fast is over, diluted fruit juices (freshly squeezed oranges, real grapefruits, etc.) and various broths are the way to go for about the first three or four days. Your digestive system has been 'asleep' for quite some time, and the last thing it needs is to be jarred back into action abruptly. Your stomach has also decreased in size, and if you eat too much too soon, you might feel bloated and (in the case of some fasters I know) make the mistake of binge eating.

The fasters with whom I associate then introduce solid foods (never protein at first) gradually over the next three or four days. Some people introduce (as their first solid food) fresh fruit first, and then work their way toward salads and other (now non-diluted) juices and broths. The reason you don't introduce protein initially has to do with the body needing fuel (carbohydrates) rather than structure (protein) first and foremost. The worst thing one could do would be to eat steak the first day after a long fast.

All of that being said, some people can break their fasts less gently than this, and I tend to be one of those people. I usually break my fasts with solid food the first or second day. It is not unusual, for example, for me to consume two or three slices of homemade pizza after I have had some kind of broth early during the first day. I let that settle and see how I feel. I suppose that it is easier for some people to break their fasts than for others. But I would err on the side of caution if one has fasted for longer than (e.g.) seven days.

 

[Sam Posten]

Scott, I just ask you to step back a second and read what you have written as someone who isn't completely taken with the ideas of fasting. You are describing things that sound almost delusional.

To reiterate, biofeedback always ought to take precedence over a predetermined amount of time to fast. In my four-plus years of fasting, I have become aware of various signals ('feedback,' if you will) and I know when I ought to fast and when I ought not to fast. One of the doctors with whom I correspond frequently reminds me that biofeedback trumps theory.

So this is a tightrope walk? What happens if you accidentally miss signals or your body is too weak to broadcast them?Imagine that a very large number of people were to undertake your program, what percentage of people do you believe would physically harm themselves pursuing this?

I attribute this to more oxygen being routed to the brain, although that is speculation on my part. It may be in part because the body does not have to work virtually every minute of every day digesting food (a physiological process that seems to take a large amount of energy for our bodies to accomplish). I do like the lower metabolic rate (this is actually one of the reasons I began running back in the 1970s -- more on this later if you wish) when one gives their digestive system a rest. A lower metabolism is something one can 'feel' -- especially for someone like myself who over the past thirty-five years has become very attuned to his body (e.g., active and resting pulse, blood pressure, and various other cardio-related aspects including atrial fibrillation and ventricular tachycardia). Some of the evidence seems to suggest that a lower metabolism may equate to a longer life span, and this is very intriguing to me.

You keep using that word "evidence", I don't think it means what you think it means. You are taking anecdotal data and putting your own non medical terms into play as tho they are generally accepted medical beliefs.

 

[Ockeghem]

I am working on amassing some scholarly articles on some of the topics that have been discussed thus far in this thread. This will take me some time, and I don't have a lot of that right now. But I found one this morning that intrigued me greatly. I don't know if these links will work for non-subscribers.http://www.ncbi.nlm.nih.gov/pubmed/22391012Lee, C., Raffaghello, L., and Longo, VD. "Starvation, detoxification, and multidrug resistance in cancer therapy."
Source: Andrus Gerontology Center, Dept of Biological Sciences and Norris Cancer Center, University of Southern California, 3715 McClintock Avenue, Los Angeles, CA 90089-0191, United States.
From the abstract:
"We discuss how the remarkable changes in the levels of glucose, IGF-I, IGFBP-1 and in other proteins caused by fasting have the potential to improve the efficacy of chemotherapy against tumors by protecting normal cells and tissues and possibly by diminishing multidrug resistance in malignant cells."

What I find particularly intriguing about this is that my friend (a medical doctor who has run a fasting clinic since the late 1970s) has been telling me for some time that when the body begins to break down the fat for fuel during fasting, the bad or damaged cells are discarded before the good or undamaged ones are. He has maintained for years that his patients with cancer have improved greatly (either gone into remission or have seen the cancer disappear entirely) when they have fasted. He has also said that their need for various medications has decreased.One of the things I was very interested in observing during my last fast was this. When I was five years old, I fell on a pile of glass, cutting a section between my right wrist and elbow. The scar has been with me for fifty years. During my last fast, I was paying very close attention to this scar because I have read that during a prolonged fast (namely after the third week or so), the real 'healing' of various tissues at the cellular level begins. Although I still have the scar to some extent, one thing became very apparent to me, and that is that the scar has gotten smaller (yes, I measured it), the protrusion has lessened, and it has faded to a large extent. I found this quite interesting.

 

[Ockeghem]

Scott, I just ask you to step back a second and read what you have written as someone who isn't completely taken with the ideas of fasting. You are describing things that sound almost delusional.So this is a tightrope walk? What happens if you accidentally miss signals or your body is too weak to broadcast them?Imagine that a very large number of people were to undertake your program, what percentage of people do you believe would physically harm themselves pursuing this?You keep using that word "evidence", I don't think it means what you think it means. You are taking anecdotal data and putting your own non medical terms into play as tho they are generally accepted medical beliefs.

Sam,I am not advocating that people do this. But I do have a Ph.D. and over thirty publications in my chosen field of study and know how to conduct research. Perhaps you ought to read my posts more carefully. Read: "speculation on my part," "it may be," "I believe that," etc. I do know what empiricism means, though. And that is evidence, although not the evidence you choose to accept probably because I have never taken the time to attempt to publish it. I am not a medical doctor, and I thought that I had made that abundantly clear.If what I have written in this thread sounds delusional to you, that is your choice to believe that. If you want this thread closed and the content deleted, please talk to a moderator or an administrator and have it done.

 

[Sam Posten]

Actually I -have- talked to the owners about this and they are fine with it remaining open so long as we are civil in our discussions. I've honored that and am intrigued by the discussion and would like to hear you out further, but I won't mask my belief that long term fasting is dangerous to the body as a whole.To be clear: I don't doubt you have done your research and I am not impugning your credentials.The journal article you listed is an extension of my frustration with this discussion tho: Sure there may be some help to those cancer patients but what other damage is happening to their bodies that isn't being noted? What are the long term deleterious effects, if any, of extended fasting? How dangerous is long term fasting to the average human?

 

[Ockeghem]

"The journal article you listed is an extension of my frustration with this discussion tho: Sure there may be some help to those cancer patients but what other damage is happening to their bodies that isn't being noted? What are the long term deleterious effects, if any, of extended fasting? How dangerous is long term fasting to the average human?"

Sam,

You ask some very intriguing questions. I will continue to dig. And you should as well, and formulate your own conclusions based on the evidence you do or do not find. It may very well be that published studies on long-term fasting and the (ostensibly) deleterious effects and/or how dangerous long-term fasting might be to humans has not yet been researched. You have your new research topic!

"... but I won't mask my belief that long term fasting is dangerous to the body as a whole."

Okay, so long as it's just a belief of yours and not based on actual evidence, I'm fine with that.

Here is one of the aspects of fasting that I find absolutely fascinating. I have read that regular fasting lowers the metabolic rate, and as such it may prolong one's lifespan. I know for a fact that it lowers the metabolism -- I've measured my blood pressure and taken six or seven (active and resting) heart rates per day during my short and long-term fasts.

Anton, S. and Leeuwenburgh, C. "Fasting or caloric restriction for Healthy Aging."

Source:

Exp Gerontol. 2013 Apr 29. pii: S0531-5565(13)00118-6. doi: 10.1016/j.exger.2013.04.011. [Epub ahead of print]

University of Florida, Department of Aging and Geriatric Research, Institute on Aging, Gainesville, FL, United States. Electronic address: [email protected].


http://www.ncbi.nlm.nih.gov/pubmed/23639403

I am very gratified to see that intermittent fasting is becoming more visible in various branches of medicine.

From the abstract (the underlining is mine):

Aging is associated with a host of biological changes that contribute to a progressive decline in cognitive and physical function, ultimately leading to a loss of independence, and increased risk of mortality. To date, prolonged caloric restriction (i.e., a reduction in caloric intake without malnutrition) is the only non-genetic intervention that has consistently been found to extend both mean and maximal life span across a variety of species. Most individuals have difficulty sustaining prolonged caloric restriction, which has led to a search for alternative approaches that can produce similar to benefits as caloric restriction. A growing body of evidence indicates that fasting periods and intermittent fasting regimens in particular can trigger similar biological pathways as caloric restriction. For this reason, there is increasing scientific interest in further exploring the biological and metabolic effects of intermittent fasting periods, as well as whether long-term compliance may be improved by this type of dietary approach. This special will highlight the latest scientific findings related to the effects of both caloric restriction and intermittent fasting across various species including yeast, fruit flies, worms, rodents, primates, and humans. A specific emphasis is placed on translational research with findings from basic bench to bedside reviewed and practical clinical implications discussed.

 

[Ockeghem]

Here is another article on calorie restriction and aging. As I said, this is one of the most fascinating aspects of fasting to me.

Kitada, M., Kume, S., Takeda-Watanabe, A., Tsuda, S., Kanasaki, K., and Koya, D. "Calorie restriction in overweight males ameliorates obesity-related metabolic alterations and cellular adaptations through anti-aging effects, possibly including AMPK and SIRT1 activation."

Source:
Biochim Biophys Acta. 2013 Oct;1830(10):4820-7. doi: 10.1016/j.bbagen.2013.06.014. Epub 2013 Jun 23.Diabetology and Endocrinology, Kanazawa Medical University, Uchinada, Ishikawa 920-0293, Japan.

Abstract
Calorie restriction (CR) is accepted as an experimental anti-aging paradigm. Several important signal transduction pathways including AMPK and SIRT1 are implicated in the regulation of physiological processes of CR. However, the mechanisms responsible for adaptations remain unclear in humans.

SCOPE OF REVIEW:
Four overweight male participants were enrolled and treated with 25% CR of their baseline energy requirements for 7 weeks. Characteristics, including body weight (BW), body mass index (BMI), %fat, visceral fat area (VFA), mean blood pressure (MBP) and VO2 max, as well as metabolic parameters, such as insulin, lipid profiles and inflammatory makers and the expression of phosphorylated AMPK and SIRT1 in peripheral blood mononuclear cells (PBMNCs), were determined at baseline and then after 7weeks. In addition, we assessed the effects of the serum collected from the participants on AMPK and SIRT1 activation and mitochondrial biogenesis in cultured human skeletal muscle cells.|MAJOR CONCLUSIONS:After CR, BW, BMI, %fat, VFA and MBP all significantly decreased, while VO2 max increased, compared to those at baseline. The levels of fasting insulin, free fatty acid, and inflammatory makers, such as interleukin-6 and visfatin, were significantly reduced, whereas the expression of phosphorylated AMPK and SIRT1 was significantly increased in PBMNCs collected after CR, compared to those at baseline. The skeletal muscle cells that were cultured in serum collected after CR showed an increase in AMPK and SIRT1 activity as well as mitochondrial biogenesis.

GENERAL SIGNIFICANCE:
CR is beneficial for obesity-related metabolic alterations and induces cellular adaptations against aging, possibly through AMPK and SIRT1 activation via circulating factors.