This article had been discussed here back when it came out: Evidence against Calorie Restriction.
And importantly, it's a well-known effect that's already taken into account by CR scientists.
"Having unlimited access to food makes the animals prone to cancer, type-2 diabetes, and renal failure; it alters their gene expression in substantial ways; and it leads to cognitive decline."
It seems mice are affected in the same way as humans are when they overeat. Does that mean that all previous laboratory research that used mice as a trial organism is only applicable to overweight humans?
And if ~80% of research is done using mice as a viable replacement for humans, then how do we know so little about mouse health? Is it reflective of how much we know of human health?
Finally, college students across the country are fed in a extremely similar way to these mice (except they may have to walk a block or two in order to obtain food). Could research show us that we are actually making college students less intelligent due to the apparent decrease in their health from overeating? Seems backwards...
From the author profile:
Mattson traces his interest in aging back to his ninth-grade classroom. Asked then to write an essay on a scientific topic of his choice, he picked cryopreservation—the futuristic concept that humans can be resurrected after being suspended in the deep freeze for years. "I was grabbed with the idea of putting aging on hold," he now says.
The question is, does he post on Less Wrong?
Thanks very much for the link-- that's a story of ill-thought-out optimization that will probably come in handy as an example as well as for the specifics.
However, it's possible to be fat and healthy. Note that the mice aren't just eating ad libitum, they're also sedentary, and I'd be willing to bet that their food has the minimal nutrients needed to let them get by-- not comparable to the food they'd eat in the wild. It may also be relevant that they're not in the sort of sensory environment they evolved in.
It appears that standard lab rats and mice are all morbidly obese. Using them as model organisms may give misleading results that fail to transfer to humans, or even to healthy rats and mice.
Or it may give extremely accurate results. Have you walked around in a mall lately, and actually looked at people?
(Here's hoping the rest of the world isn't getting as portly as the US.)
Try a little less confirmation bias the next time you go to a mall, and I think you'll see people at a range of apparent fat percentages and body weights.
It appears that standard lab rats and mice are all morbidly obese. Using them as model organisms may give misleading results that fail to transfer to humans, or even to healthy rats and mice.
Article in the Slate.
PNAS version.
Does this reduce the whole calorie-restriction thing to nothing more than the advice to not be a fat slob? Well, maybe not, according to the author, but it has to make one wonder.