The Calorie-Restriction Experiment | Hacker News Reader

The Calorie-Restriction Experiment

nytimes.com

47 pointsars11 comments

"By slowing aging and increasing resistance to disease during periods of food scarcity, the adaptive responses to fewer calories increased the odds that animals and humans that lived short lives might survive until they could reproduce."

This statement seems somewhat dangerous to me. If the body slows down because of lack of resources, I'm willing to bet that, like has been observed in animals, fertility will also drop off - you don't reproduce when resources are scarce.

The article seems kind of contradictory to me. They say that it isn't a study about weight loss but then go on to say that this diet has an effect on lifespan in part because of the effect of aging diseases (cancer, cardiovascular disease, diabetes) which are all highly correlated with being overweight. Weight loss therefore has to be one of the primary goals of the study - if it didn't help you lose weight then it wouldn't (by definition) be reducing your risk factors for those diseases.

I think the idea is that the animals would have a better chance of surviving until food became plentiful again, at which point their intake would return to normal along with fertility and aging.

Oh I don't disagree but I mean to point out that engaging in a calorie restricting diet at a young age may be detrimental to fertility, based on the effects that they suggest and the observational evidence from other animals. This may or may not be a big deal to certain people depending on goals - if you want to have children in your 20s versus 30s for example.

Yeah,

After a reading this article,

http://hplusmagazine.com/articles/forever-young/eldorado-des...

I could see calorie restriction really had little basis and moreover, little logic, to it.

But also, I'm 40+, 6', 135 pounds and I eat as much as I possibly can. I'm probably on the high of high metabolism. Losing 15% of body weight for me would, uh, really bad. And that's the thing, there's lot of genetic variation concerning gain weight propensity and a lot environmental variation concerning diet and level of activity. NONE of this is apparent in lab-animal studies. Lab animals are genetically uniform creatures who just sit around and eat dull food, even for a mouse (or monkey or whatever). If you've lived like a lab animal so-far, time to get out a bit but otherwise, the conclusions might not be warranted.

I agree. All subjects interviewed in the article view this as a change in their diet. And calories and diet are not independent. The topic is very interesting. I searched for the original research paper but could not find it.

The benefits of calorie restriction are only partially caused by carrying less fat (specifically visceral fat that triggers higher levels of chronic inflammation). Here is a demonstration of what happens when you remove visceral fat from mice, for example. You get life extension, but not as much as calorie restriction:

http://www.fightaging.org/archives/2008/03/lose-the-visceral...

Calorie restriction is doing other things to metabolism as well. For example, autophagy is upregulated by calorie restriction. Upregulating autophagy by other means enhances life span. See:

http://www.fightaging.org/archives/2009/10/attention-paid-to...

http://www.fightaging.org/archives/2007/10/calorie-restricti...

There are probably other line items as well, but given that calorie restriction doesn't work in animals with disabled autophagy mechanisms, it's the place to be looking. The plausible theory would be that increased autophagy cleans up damaged mitochondria, and mitochondrial function and damage are clearly very important determinants of longevity. See:

http://www.fightaging.org/archives/2006/10/how-age-damaged-m...

http://www.fightaging.org/archives/2008/01/revisiting-skulac...

There are some review articles that are very readable for non-scientists written by an old boss of mine (Dr. Mark Mattson at the National Institute on Aging) on dietary intake.

Here are some:

Dietary factors, hormesis and health http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2253665?tool=pub...

Impact of energy intake and expenditure on neuronal plasticity. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2635925/?tool=pu...

Mattson is an interesting (albeit, a bit harebrained) dude. He completely believes in this caloric restriction stuff so much that he lives the lifestyle and follows a really strict diet.

Hmm,

Do you know if there have been any studies which made an effort to distinguish average-weight and average calorie intake? Hight calorie intake is associate with obesity and obesity is associated with many health problems. But what is the cause and what is the effect?

Do, say, long distance athletes, who consume and use massive calorie levels, suffer the same health problems as overweight sedentary people? Seriously, I'm curious if people have looked this.

If the subject is losing weight then he/she is getting low calories and the body is burning excess fat. The diet then can be adjusted by trial and error and the subject can find the right diet and the right amount. The golden rule is to eat as much non-processed food as possible. I believe that these professional doctors hyper-complicated the process. Dieters usually hate to count calories.

The study isn't about weight loss.

Natrius is right. The independent variable in this experiment is calories ingested, not weight loss. They're specifically testing for what happens when you eat fewer calories. On page six, they compare rats that are lean because of exercise with rats that are lean because of calorie restriction. "...only calorie restriction was able to slow down aging and increase maximal life span." Simply having the participants lose weight would not allow as much to be learned about what they are studying. Complex controls are paramount for these human studies.

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