16 replies to this topic

[Michael]

All:

As previously documented to death, alternate day fasting (ADF -- AKA EOD, Intermittent Fasting (IF)), etc provides no lifespan benefit to normal, healthy, well-fed, non-toxin-megadosed, non-genetically-fucked-up rodents, except to the degree there is a concomitant reduction in Calorie intake; and, even the favorable-looking short-term health risk factor shifts observed in EOD in rodents are mostly not observed in humans. Two recent studies, found by Al Pater on the CR Society list, find that EOD is also not protective against model prostate cancer in mice.

Caloric restriction (CR) delays cancer growth in animals, though translation to humans is difficult. We hypothesized intermittent fasting (i.e., intermittent extreme CR), may be better tolerated and prolong survival of prostate cancer (CaP) bearing mice.

METHODS: We conducted a pilot study by injecting 105 male individually-housed SCID [immunodeficient] mice with LAPC-4 cells. When tumors reached 200 mm(3), 15 mice/group were randomized to one of seven diets and sacrificed when tumors reached 1,500 mm(3): Group 1: ad libitum 7 days/week; Group 2: fasted 1 day/week and ad libitum 6 days/week; Group 3: fasted 1 day/week and fed 6 days/week via paired feeding to maintain isocaloric conditions to Group 1; Group 4: 14% CR 7 days/week; Group 5: fasted 2 days/week and ad libitum 5 days/week; Group 6: fasted 2 day/week and fed 5 days/week via paired feeding to maintain isocaloric conditions to Group 1; Group 7: 28% CR 7 days/week. Sera from mice at sacrifice were analyzed for IGF-axis hormones.

RESULTS: There were no significant differences in survival among any groups. However, relative to [AL], there were non-significant trends for for improved survival for Groups 3 (HR 0.65, P = 0.26), 5 (0.60, P = 0.18), 6 (HR 0.59, P = 0.16), and 7 (HR = 0.59, P = 0.17). Relative to Group 1, body weights and IGF-1 levels were significantly lower in Groups 6 and 7.

CONCLUSIONS: This exploratory study found non-significant trends toward improved survival with some intermittent fasting regimens, in the absence of weight loss. Larger appropriately powered studies to detect modest, but clinically important differences are necessary to confirm these findings.(1)

Ie, despite the lack of a significant effect, with only 15 animals per group, it's reasonable to suspect that this was just an artifact of the study being underpowered, and that there might be some there there. This is especially so since "mild" CR has been shown in several previous studies to be protective in a range of prostate cancer models, and yet in this study its nominal "benefit" did not reach statistical significance, despite being tied for the largest numerical hazard ratio reduction and p-value.

So, they did another study, using only the promising-looking twice-weekly fasting group, and including more animals in each arm:

We sought to confirm these findings in a larger study. A total of 100 (7- to 8-week-old) male severe combined immunodeficiency mice were injected subcutaneously with 1 x 10(5) LAPC-4 prostate cancer cells. Mice were randomized to either ad libitum Western Diet (44% carbohydrates, 40% fat and 16% protein) or ad libitum Western Diet with twice-weekly 24 h fasts (IF). ... Overall, there was no difference in mouse survival (P=0.37) or tumor volumes (P>/=0.10) between groups. Mouse body weights were similar between arms (P=0.84). IF mice had significantly higher serum IGF-1 levels and IGF-1/IGFBP-3 ratios at killing (P<0.001). [Mattson has reported this same finding, exactly the opposite of CR proper -MR] However, no difference was observed in serum insulin, IGFBP-3 or tumor phospho-Akt levels (P>/=0.39). IF did not improve mouse survival nor did it delay prostate tumor growth.

This may be secondary to metabolic adaptations to the 24 h fasting periods. Future studies are required to optimize CR for application in humans.

Full texts are linked by PMID below.


References
1. Effect of intermittent fasting with or without caloric restriction on prostate cancer growth and survival in SCID mice. Buschemeyer WC 3rd, Klink JC, Mavropoulos JC, Poulton SH, Demark-Wahnefried W, Hursting SD, Cohen P, Hwang D, Johnson TL, Freedland SJ. Prostate. 2010 Feb 17. [Epub ahead of print] PMID: 20166128

2. Effect of intermittent fasting on prostate cancer tumor growth in a mouse model. Thomas JA 2nd, Antonelli JA, Lloyd JC, Masko EM, Poulton SH, Phillips TE, Pollak M, Freedland SJ. Prostate Cancer Prostatic Dis. 2010 Aug 24. [Epub ahead of print] PMID: 20733612

[VidX]

I get an impression that a "decent" fasting is at least 6-7 days, from time to time. As just after some time changes in energy sources and other stuff start to happen. It'd be an interesting experiment with a prolonged fasting..

[Sillewater]

What worries me is the increased in IGF-1 that keeps popping up with IF regimen. Great for building muscle, but not for longevity. Thanks Michael for keeping us up to date on interesting research.

Edited by Sillewater, 29 November 2010 - 06:09 AM.

[xEva]

We examined urinary ketones to measure energy substrate use in the absence of dietary glucose (that is, when fasted). We found that though IF mice initially had significantly higher ketone levels than ad libitum mice, with each successive fast, IF mice became progressively less ketotic ultimately approaching urinary ketone levels observed in ad libitum mice. IGF-1 has been proposed to positively impact serum glucose control.41, 42, 43 We hypothesize that increased levels of IGF-1 in IF mice served to facilitate improved glucose uptake. This gradual improvement in glucose uptake could be reflected by decreased urinary ketone levels, as seen in this study. This 'normalization' of urinary ketone levels could reflect improved glucose use by the host and possibly the tumor. As such, it remains possible the negative findings from this study stem from the mouse's ability to adapt to 24h fasting periods by regulating its metabolism, though this requires further study.

What glucose uptake? The one that was not there to begin with?

It is one thing when lay people do not understand the metabolism of fasting, it's entirely different when researchers that supposedly study it do not get it. Ketones in urine is the same as glucose in urine. Namely, when the body has hard time utilizing either one, kidneys will remove excess from plasma. Owen and Cahill showed back in the 1960s that when the body adapts to ketosis, ketonuria drops dramatically, while ketones levels in plasma remain high or even keep on growing (certainly in humans).

The other sad aspect of this hurried studies (the first one took about 4 weeks, and I could not quickly spot the length of the second one) is that within 6 variations, which they compared to ad lib, they did not implement an overall CR with 1 fast per week. Or at least they should have restricted food on the days immediately following the fast. In other words, those mice were not prevented from binge-eating following their fasts, which, everyone in the human fasting circles knows, negates the benefits of a fast.

Edited by Michael, 18 December 2010 - 01:09 PM.
Clean quote for readability

[JohnD60]

To OP's broader point... "alternate day fasting (ADF -- AKA EOD, Intermittent Fasting (IF)), etc provides no lifespan benefit to normal, healthy, well-fed, non-toxin-megadosed, non-genetically-fucked-up rodents, except to the degree there is a concomitant reduction in Calorie intake" ...I confess to being confused and a little discouraged by researchers' failure to document life span extensions in rodents resulting from IF. But there seems to be significant documentation (http://cat.inist.fr/...cpsidt=17160045)(http://www.jnutbio.c...e/S0955-2863(04)00261-X/abstract), just to site two, that IF enhances some processes, particularly Mitochondrial processes.

So how does one reconcile these apparently contradictory results? Some possible explanations:
1. The rodents don't understand what is going on, one day they are being feed, the next their food disappears, the chronic stress of this irregular (from their perspective) feeding pattern has an adverse effect on their health which offsets the benefits of IF.
2. The rodents compensate after x hours of not being feed by becoming sedentary, which off sets the benefits of IF.
3. ?
4. ?

So, since I believe in the Mitochondrial Theory of aging, I place a lot of weight upon the rodent studies that show enhancements to Mitochondrial function as a result of IF, and I discount the rodent studies that fail to show an extension of live span resulting from IF as being in some way uniformly flawed.

Edited by JohnD60, 18 December 2010 - 03:32 AM.

[niner]

I think that prevention of post-fast binge eating would have been an important addition, as xEva points out. My strongest initial take on this, though, was the poor applicability of the model to a normal human situation: SCID mice with implanted pCa? Seems like the very definition of genetically fucked up...

[Michael]

We examined urinary ketones to measure energy substrate use in the absence of dietary glucose (that is, when fasted). [...] We hypothesize that increased levels of IGF-1 in IF mice served to facilitate improved glucose uptake. This gradual improvement in glucose uptake could be reflected by decreased urinary ketone levels, as seen in this study.

What glucose uptake? The one that was not there to begin with?

If glucose levels actually declined to zero, the animals would be dead. Only some organs can operate well on ketones; fasting leads to gluconeogenesis, not just ketogenesis.

To OP's broader point... "alternate day fasting [...] provides no lifespan benefit to normal [...] rodents, except to the degree there is a concomitant reduction in Calorie intake" ...I confess to being confused and a little discouraged by researchers' failure to document life span extensions in rodents resulting from IF. But there seems to be significant documentation (http://cat.inist.fr/...cpsidt=17160045)(http://www.jnutbio.c...e/S0955-2863(04)00261-X/abstract), just to site two, that IF enhances some processes, particularly Mitochondrial processes.

So how does one reconcile these apparently contradictory results?

In the specific example you're citing, the animals actually did lose weight as a result of the EOD fasting, and thus were probably actually CRed, despite what the abstract says. This, as documented many times before, is a chronic flaw in the reporting of EOD studies. More broadly, however: An intervention can cause favorable (or favorable-looking) short- or even long-term changes in some aspects of metabolism, while causing deleterious ones in either. The rise in IGF-1 in response to EOD, already noted by Silewater, is an example; so are many drugs that reduce a risk factor for a particular disease, but raise the total mortality rate.

Also I discount the rodent studies that fail to show an extension of live span resulting from IF as being in some way uniformly flawed.

Then you're discounting all of the evidence on the subject . Interventions for use today should be evaluated on the basis of existing evidence, even if new experiments for the future can be designed to probe possible flaws in those studies. Do you have any specific critiques of the methods or models used in past experiments, against which you can propose an alternative design to better evaluate EOD?

I think that prevention of post-fast binge eating would have been an important addition, as xEva points out. My strongest initial take on this, though, was the poor applicability of the model to a normal human situation: SCID mice with implanted pCa? Seems like the very definition of genetically fucked up...

The problem is that pCa is incredibly rare in wild-type rodents, so if you want to study pCa specifically, you need to use a special model. However, multiple studies have looked at the effects of EOD on naturally-occurring cancers in "normal, healthy, well-fed, non-toxin-megadosed, non-genetically-fucked-up rodents," and the results are as described: null, except inasmuch as EOD leads to CR in that experiment.

Edited by Michael, 18 December 2010 - 01:31 PM.

[xEva]

We examined urinary ketones to measure energy substrate use in the absence of dietary glucose (that is, when fasted). [...] We hypothesize that increased levels of IGF-1 in IF mice served to facilitate improved glucose uptake. This gradual improvement in glucose uptake could be reflected by decreased urinary ketone levels, as seen in this study.

What glucose uptake? The one that was not there to begin with?

If glucose levels actually declined to zero, the animals would be dead. Only some organs can operate well on ketones; fasting leads to gluconeogenesis, not just ketogenesis.

With all due respect, and your superb knowledge of supplements notwithstanding, your ignorance of the subject of fasting amazes me. It amazes me even more that ImInst would spend their hard-collected money to support "research" of fasting by equally ignorant "researchers". If I didn't know better, I could assume that your a priori goal was to poo-poo fasting in all forms and at all cost.

It is obvious from reading that ahead-of-being-rejected-by-any-reputable-journal report quoted above that the "researchers" were perplexed by the disappearance of ketones from urine after mice have adapted to fasting. It is also obvious that they assumed that this was the sign that mice were no longer in ketosis but fed on endogenously produced glucose (whose "uptake was facilitated by IGF-1"), which is a superb delusion in itself, for it implies that they believe that a very small amount of glucose produced by murine livers was sufficient to sustain them in their fast. A sort of a "miracle of feeding the multitudes with five loaves" here..

FACT: Mice eat 1/4 to 1/3 of their weight daily. How much protein --nay, muscles!-- your super-mice should have to sustain them in their fasts, if it were not for ketosis? Even in ketosis of starvation, these animals do not last long. I recall a phrase in one report that said "more than half of them died on the 3rd day" and my impression is that some rare murine champions may last close to a week. Provided they are in ketosis, of course; otherwise, they should be dead by the end of their first 24 hours.

Only some organs can operate well on ketones; fasting leads to gluconeogenesis, not just ketogenesis.

Another superb delusion. ALL CELLS WITH MITOCHONDRIA operate better and more efficiently on ketones than on glucose. There are relatively very few cells in the human body that dependent entirely on glucose, which, on top of it, is recycled during fasting. If it were not for it, an average man would die after the first week of fasting due to protein losses incompatible with life, instead of lasting over 2 months.

Sad..

Edited by xEva, 18 December 2010 - 06:19 PM.

[Michael]

We examined urinary ketones to measure energy substrate use in the absence of dietary glucose (that is, when fasted). [...] We hypothesize that increased levels of IGF-1 in IF mice served to facilitate improved glucose uptake. This gradual improvement in glucose uptake could be reflected by decreased urinary ketone levels, as seen in this study.

What glucose uptake? The one that was not there to begin with?

If glucose levels actually declined to zero, the animals would be dead. Only some organs can operate well on ketones; fasting leads to gluconeogenesis, not just ketogenesis.

It amazes me even more that ImInst would spend their hard-collected money to support "research" of fasting by equally ignorant "researchers".

What fasting research or researchers is Imminst supporting?

FACT: Mice eat 1/4 to 1/3 of their weight daily. How much protein --nay, muscles!-- your super-mice should have to sustain them in their fasts, if it were not for ketosis?

I don't think anyone is disputing that ketosis generates an important energy source during fasting; I was only pointing out that it isn't the only such energy source, or the best energy source for all cells, thus explaining why ketotic animals still have non-zero blood glucose, which finding evidently stumped you, above.

Only some organs can operate well on ketones; fasting leads to gluconeogenesis, not just ketogenesis.

Another superb delusion. ALL CELLS WITH MITOCHONDRIA operate better and more efficiently on ketones than on glucose. There are relatively very few cells in the human body that dependent entirely on glucose

Please document the former assertion. As to the latter: I agree that very few cells in the human (or mouse) body depend entirely on glucose; that isn't at issue. What's at issue is (a) why glucose levels in these ketotic mice were not zero, as seems to have stumped you, and (b) whether all cells in the body operate well on ketones (or even "best," as you here assert).

Free fatty acids and ketone bodies can be used as substrates for energy production by most tissues in which their utilization is to a large extent proportional to their concentration in the circulation (21, 22). Because the total oxidation of substrate is limited by the energy expenditure, elevation of FFA and KB levels will reduce the consumption of glucose for energy production in the body (2, 23, 24). The extent to which glucose can be spared is demonstrated during prolonged starvation, when glucose oxidation is reduced to some 50 g/day (25, 26). In reducing glucose outflow, FFA and KB tend to elevate the levels of glucose, and they are thus able to indirectly promote insulin secretion (24).[1]

Reference
1: Flatt JP, Blackburn GL. The metabolic fuel regulatory system: implications for protein-sparing therapies during caloric deprivation and disease. Am J Clin Nutr.
1974 Feb;27(2):175-87. Review. PubMed PMID: 4204849.

Edited by Michael, 18 December 2010 - 07:43 PM.
Inserting quote & ref

[JohnD60]

Then you're discounting all of the evidence on the subject . Interventions for use today should be evaluated on the basis of existing evidence, even if new experiments for the future can be designed to probe possible flaws in those studies. Do you have any specific critiques of the methods or models used in past experiments, against which you can propose an alternative design to better evaluate EOD?

I am discounting all of the IF 'longevity' studies on rodents as being in some way uniformly flawed, yes, that is correct.

Since I don't put my opinions out there as an advocate or an expert, I will evaluate my personal interventions any way I want. I didn't state my opinions as fact.

No, I don't have any specific critiques of the methods or models used, I thought I had made that clear. I assert that it isn't reasonable to suppose that I should, I don't have experience in rodent studies, nor was I present during the studies. I'm not going to micro manage rodent longevity experiments. Absence of a specific critique is not evidence of absence.

[capsun]

What glucose uptake? The one that was not there to begin with?

IF mice eat larger meals.

[woly]

Michael, do you see any potential uses for EOD fasting besides as a CR strategy? I have been reading the Perfect Health Diet blog which has been writing about EOD fastings potential to up regulate neuronal autophagy and the immune system. What are your thoughts on this?

[xEva]

I don't think anyone is disputing that ketosis generates an important energy source during fasting; I was only pointing out that it isn't the only such energy source, or the best energy source for all cells, thus explaining why ketotic animals still have non-zero blood glucose, which finding evidently stumped you, above.

Evidently stumped me? Are you serious? ...is all you got from our discourse?

and... why, do I make an impression that I would not know such trivia? The fact that the body always maintains a minimal glucose level is covered not even in the introductory college courses but somewhere... in junior high?

And so, no, I was not "stumped" by it. I was rather astounded by the blatant ignorance of the "researchers", whom for whatever reason you obviously support (already by disseminating their work "ahead of print").

It is you and your "researchers" who until now obviously did not know that ketones disappear from urine after the body adapts to ketosis. That's why they so stupidly assumed that it meant that somehow --no other but miraculously!-- that ever present minimal glucose level was enough to sustain the mice during their fasts... which in itself plenty illustrative of their lack of understanding of metabolic processes in general, hence my remark, which glucose, for it is obvious to anyone in the know that it could not possibly cover the required energy expenditure without either dipping bellow the absolutely required minimum or having the liver to supply the balance via gluconeogenesis... but then where all that required protein would come from?..

See what I mean?

ALL CELLS WITH MITOCHONDRIA operate better and more efficiently on ketones than on glucose. There are relatively very few cells in the human body that dependent entirely on glucose

Please document the former assertion.

I don't have time to look for it now. You should read Richard Veech on ketones, just google it. Another good work has ketones ugly duckling words in it. I'll post them later.

As for that 1974 work you quote, I doubt those researchers would appreciate you making them look stupid by quoting a badly worded sentence, which your emphasis made look as if they said that FFAs and ketones elevate glucose levels, while in fact what they meant was that FFAs and ketones spare glucose by providing an alternate source of energy.




.

Edited by xEva, 19 December 2010 - 04:13 PM.

[xEva]

Here are the promised refs. Both are very good reviews and an easy read.

Ketones: Metabolism’s Ugly Duckling PDF 2003

Theodore VanItallie and Thomas Nufert


Ketone Bodies, Potential Therapeutic Uses PDF 2001

Richard Veech, Britton Chance, Yoshihiro Kashiwaya, Henry Lardy, George Cahill

Edited by Michael, 23 December 2010 - 09:22 PM.
Correcting Veech pub. date per xEva

[Michael]

First, my apologies for xEva: I wasn't trying to misrepresent your objection; I honestly didn't decipher the basis on which you were making it. IAC, I have to say that it's somewhat of a moot point: taking ketosis and metabolism generally as a black box, you still get fasting in ---> no prostate cancer prevention out. And as previously posted by Brett B,

When subjected to only 16 hours without food (considerably less than that experienced by the average CR'ed rodent), rats lose an average of 6.9% body weight, their serum glucose concentrations drop by an average of 34.9%, triglycerides drop by 48.4% and cholesterol drops by 21.7%(3). CR'ed rats deplete their glycogen stores during the period of fasting between meals and transition into a daily state of ketosis, as well as experiencing hypothermia during this period(11). Mice rapidly switch to fatty acid oxidation(and ketosis) for fuel after just 6 hours without food(12). ... Taking into consideration these ratios [of differential physiological and metabolic responses to fasting], along with the known feeding patterns of rodents on CR, it could be suggested that the approximately 20 hours of fasting that regular CR'ed rodents experience on a daily basis, is equivalent to 120 to 200 hours of fasting for a human(5 to 8 days.)

... so the point seems to me to be 'doubly moot.'

Michael, do you see any potential uses for EOD fasting besides as a CR strategy? I have been reading the Perfect Health Diet blog which has been writing about EOD fastings potential to up regulate neuronal autophagy and the immune system. What are your thoughts on this?

From available evidence, no: first, again, as I've indicated previously, Cuervo has data (which she keeps promising to finally get written up and published ...) showing that EOD, absent CR proper, does not fully reproduce the full spectrum of effects on autophagy observed under regular-fed CR proper. Second, it appears from limited available evidence that EOD without CR proper does not, in fact, do anything on neuronal aggregates of interest, though it evidently helps the damaged neurons to keep limping along:

we tested the hypothesis that two different energy restriction regimens, 40% calorie restriction (CR) and intermittent fasting (IF) can protect against cognitive decline in the triple-transgenic mouse model of AD (3xTgAD mice) [one of few mouse AD models that shows neurofibrillary tangles, not just beta-amyloid plaques -MR]. Groups of 3xTgAD mice were maintained on an ad libitum control diet, or CR or IF diets, beginning at 3 months of age. ... At 10 months 3xTgAD mice on the control diet exhibited reduced exploratory activity compared to non-transgenic mice and to 3xTgAD mice on CR and IF diets. Overall, there were no major differences in performance in the water maze among genotypes or diets in 10-month-old mice. In 17-month-old 3xTgAD mice the CR and IF groups exhibited higher levels of exploratory behavior, and performed better in both the goal latency and probe trials of the swim task, compared to 3xTgAD mice on the control diet. 3xTgAD mice in the CR group showed lower levels of Abeta1-40, Abeta1-42 and phospho-tau in the hippocampus compared to the control diet group, whereas Abeta and phospho-tau levels were not decreased in 3xTgAD mice in the IF group. IF may therefore protect neurons against adverse effects of Abeta and tau pathologies on synaptic function.(1)

It also appears possible there were some artifacts in this study giving the IF/EOD group better scores that were unrelated to neuronal function, related to them being more hyper: this seems likely responsible in part for their benefit on escape latency, and "the 3xTgAD IF male mice swam significantly faster than the 3xTgAD,AL male mice" (1).

Reference
1: Halagappa VK, Guo Z, Pearson M, Matsuoka Y, Cutler RG, Laferla FM, Mattson MP. Intermittent fasting and caloric restriction ameliorate age-related behavioral deficits in the triple-transgenic mouse model of Alzheimer's disease. Neurobiol Dis. 2007 Apr;26(1):212-20. Epub 2007 Jan 13. PubMed PMID: 17306982.

[health_nutty]

So, since I believe in the Mitochondrial Theory of aging, I place a lot of weight upon the rodent studies that show enhancements to Mitochondrial function as a result of IF, and I discount the rodent studies that fail to show an extension of live span resulting from IF as being in some way uniformly flawed.

When join a discussion in a public forum, you are implicitly arguing that your viewpoint is correct (factually true). It is bad logic to say that it is your opinion once you realize you can't defend your argument.

[JohnD60]

When join a discussion in a public forum, you are implicitly arguing that your viewpoint is correct (factually true).

No. Your wrong.