Guest guest Posted March 8, 2008 Report Share Posted March 8, 2008 Huffman DM, Moellering DR, Grizzle WE, Stockard CR, MS, Nagy TR. Effect of exercise and calorie restriction on biomarkers of aging in mice. Am J Physiol Regul Integr Comp Physiol. 2008 Mar 5; [Epub ahead of print] PMID: 18321952 Unlike calorie restriction (CR), exercise fails to extend maximum lifespan, but the mechanisms that explain this disparate effect are unknown. We used a 24-week protocol of treadmill running, weight matching and pair feeding to compare the effects of exercise (EX) and CR on biomarkers related to aging. This study consisted of young controls, an ad libitum-fed sedentary group, two groups that were weight matched by EX or 9% CR, and two groups that were weight matched by 9% CR+EX or 18% CR. After 24 weeks, ad libitum-fed sedentary mice were the heaviest and fattest. When comparing weight-matched groups, mice that exercised were leaner than CR mice. Ad libitum-fed EX mice tended to have lower serum IGF-1 than fully-fed controls, but no difference in fasting insulin. Mice that underwent 9% CR or 9% CR+EX, had lower insulin levels; the lowest concentrations of serum insulin and IGF-1 were observed in 18% CR mice. EX resulted in elevated levels of tissue heat shock proteins, but did not accelerate the accumulation of DNA damage. Thus, failure of exercise to slow aging in previous studies is not likely the result of increased accrual of oxidative damage, and may instead be due to an inability to fully mimic the hormonal and/or metabolic response to CR. Quote Link to comment Share on other sites More sharing options...
Guest guest Posted March 9, 2008 Report Share Posted March 9, 2008 Thanks for this study, Jeff. It seems to say that CR works because it reduces serum insulin and IGF-1, while exercise does not. This also fits well with this 2007 study in the British Journal of Nutrition: http://snipurl.com/21cot that says essentially that satiety-- or lack of hunger (in healthy individuals, but not insulin-resistant individuals) --is correlated with higher insulin levels, as well as the study mentioned in CRSupportgroup message #19795, which indicates that hunger may be a necessary condition for CR. So you know you're doing CR if you're a little bit hungry, and you're doing CRON if you are getting all the nutrition you need. Hara hachi bu, Diane --- In , Novick <jnovickrd@...> wrote: > > > Huffman DM, Moellering DR, Grizzle WE, Stockard CR, MS, Nagy TR. > Effect of exercise and calorie restriction on biomarkers of aging in > mice. > Am J Physiol Regul Integr Comp Physiol. 2008 Mar 5; [Epub ahead of > print] > PMID: 18321952 > > Unlike calorie restriction (CR), exercise fails to extend maximum > lifespan, > but the mechanisms that explain this disparate effect are unknown. > > We used a 24-week protocol of treadmill running, weight matching and > pair > feeding to compare the effects of exercise (EX) and CR on biomarkers > related > to aging. > > This study consisted of young controls, an ad libitum-fed sedentary > group, > two groups that were weight matched by EX or 9% CR, and two groups > that were > weight matched by 9% CR+EX or 18% CR. > > After 24 weeks, ad libitum-fed sedentary mice were the heaviest and > fattest. > When comparing weight-matched groups, mice that exercised were leaner > than > CR mice. Ad libitum-fed EX mice tended to have lower serum IGF-1 than > fully-fed controls, but no difference in fasting insulin. Mice that > underwent 9% CR or 9% CR+EX, had lower insulin levels; the lowest > concentrations of serum insulin and IGF-1 were observed in 18% CR > mice. EX > resulted in elevated levels of tissue heat shock proteins, but did not > accelerate the accumulation of DNA damage. > > Thus, failure of exercise to slow aging in previous studies is not > likely > the result of increased accrual of oxidative damage, and may instead > be due > to an inability to fully mimic the hormonal and/or metabolic response > to CR. > Quote Link to comment Share on other sites More sharing options...
Guest guest Posted March 10, 2008 Report Share Posted March 10, 2008 Diane - It is not clear to me what this means. Does it mean a constant hunger, even after a meal? Nick > So you know you're doing CR if you're a little bit hungry, and you're > doing CRON if you are getting all the nutrition you need. > > Hara hachi bu, > > Diane > Quote Link to comment Share on other sites More sharing options...
Guest guest Posted March 10, 2008 Report Share Posted March 10, 2008 Hi Nick, I don't think anyone knows what it means yet. I was simply pointing out the correlations between the studies about CR, serum insulin, and satiety. My last paragraph about being a little bit hungry when doing CR was a loose attempt at summarizing what I *thought* it meant, but I am by no means an expert. I doubt the experts know either, though. There's a lot left to understand. Diane > > Diane - It is not clear to me what this means. Does it mean a constant > hunger, even after a meal? > > Nick > > > > > So you know you're doing CR if you're a little bit hungry, and you're > > doing CRON if you are getting all the nutrition you need. > > > > Hara hachi bu, > > > > Diane > > > Quote Link to comment Share on other sites More sharing options...
Guest guest Posted March 10, 2008 Report Share Posted March 10, 2008 Hi folks: I recall we have had a similar discussion here at least once previously. A study was posted which (IIRC ..... it was quite some time ago) it was suggested, could be interpreted to mean that the sensation of hunger may be an integral part of the process by which the brain sends out messages to conserve resources during periods of famine. The implication being that, possibly, without the sensation of hunger the life extension benefits of CR would not materialize. This is interesting, and if true certainly would matter for those who believe in filling up on low-calorie-density foods to satiety while on CRON. If correct (and it may not be, of course) then with satiety, and without the brain genuinely believing there is famine, there may be no special CR life extension. In also recall another paper posted (regarding experiments in mice) about the same time which implied that even the smell of tasty food might be enough to reduce the beneficial effects of CR by causing the brain to suspect there really wasn't a famine after all. If I had to guess I would say these discussions may have occurred about two and a half years ago. But I do not know what key words one would need to use to find the posts in question. I do recall posts from both Francesca and me in that thread. But neither of us started the thread. Using the words "brain hunger" or something similar in an advanced search might turn up those posts. Rodney. > >> > Diane - It is not clear to me what this means. Does it mean a constant> > hunger, even after a meal?> > > > Nick> > > > > > > > > So you know you're doing CR if you're a little bit hungry, and you're> > > doing CRON if you are getting all the nutrition you need. > > > > > > Hara hachi bu,> > > > > > Diane> > >> >> Quote Link to comment Share on other sites More sharing options...
Guest guest Posted March 10, 2008 Report Share Posted March 10, 2008 Hi folks: It looks like the original post in that thread was #19795, contributed by T. Rodney. > > >> > > Diane - It is not clear to me what this means. Does it mean a> constant> > > hunger, even after a meal?> > >> > > Nick> > >> > >> > >> > > > So you know you're doing CR if you're a little bit hungry, and> you're> > > > doing CRON if you are getting all the nutrition you need.> > > >> > > > Hara hachi bu,> > > >> > > > Diane> > > >> > >> >> Quote Link to comment Share on other sites More sharing options...
Guest guest Posted March 12, 2008 Report Share Posted March 12, 2008 > Thus, failure of exercise to slow aging in previous studies is not > likely > the result of increased accrual of oxidative damage, and may instead > be due > to an inability to fully mimic the hormonal and/or metabolic > response to CR. Considering the frequent ongoing discussions on whether or not exercise can have similar effects to CR, I am surprised at the lack of discussion and/or comments in regard to this study, which as Diane pointed out, seems to confirm an earlier study, on the effects of exercise Regards Jeff Quote Link to comment Share on other sites More sharing options...
Guest guest Posted March 12, 2008 Report Share Posted March 12, 2008 Hi Jeff. Unfortunately, this study does not appear to address the real burning question, which is how significant CR vs. significant CR + exercise compare. (Calories were not restricted very much in any exercising group.) There is also still the question regarding CR, whether exercise improves average lifespan, even if it doesn't improve maximum lifespan. -Dave --- In , Novick <jnovickrd@...> wrote: > > > Thus, failure of exercise to slow aging in previous studies is not > > likely > > the result of increased accrual of oxidative damage, and may instead > > be due > > to an inability to fully mimic the hormonal and/or metabolic > > response to CR. > > Considering the frequent ongoing discussions on whether or not > exercise can have similar effects to CR, I am surprised at the lack of > discussion and/or comments in regard to this study, which as Diane > pointed out, seems to confirm an earlier study, on the effects of > exercise > > Regards > Jeff > Quote Link to comment Share on other sites More sharing options...
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