Starvation and Longevity

Sometimes, it seems as if science reporters just decide to make something a big story, even if there's no new news to report. In the last week, the link between calorie reduction and increased lifespan has been everywhere. New York Magazine was first, with an account of a dinner party eaten with people who don't actually eat. (The menu: salad followed by asparagus tips, followed by Quorn, washed down with water.) Now the WSJ and NY Times have joined the bandwagon:

In a laboratory at the Wisconsin National Primate Research Center, Matthias is learning about time's caprice the hard way. At 28, getting on for a rhesus monkey, Matthias is losing his hair, lugging a paunch and getting a face full of wrinkles.

Yet in the cage next to his, gleefully hooting at strangers, one of Matthias's lab mates, Rudy, is the picture of monkey vitality, although he is slightly older. Thin and feisty, Rudy stops grooming his smooth coat just long enough to pirouette toward a proffered piece of fruit.

Tempted with the same treat, Matthias rises wearily and extends a frail hand. "You can really see the difference," said Dr. Ricki Colman, an associate scientist at the center who cares for the animals.

What a visitor cannot see may be even more interesting. As a result of a simple lifestyle intervention, Rudy and primates like him seem poised to live very long, very vital lives.

This approach, called calorie restriction, involves eating about 30 percent fewer calories than normal while still getting adequate amounts of vitamins, minerals and other nutrients. Aside from direct genetic manipulation, calorie restriction is the only strategy known to extend life consistently in a variety of animal species.

How this drastic diet affects the body has been the subject of intense research. Recently, the effort has begun to bear fruit, producing a steady stream of studies indicating that the rate of aging is plastic, not fixed, and that it can be manipulated.

In the last year, calorie-restricted diets have been shown in various animals to affect molecular pathways likely to be involved in the progression of Alzheimer's disease, diabetes, heart disease, Parkinson's disease and cancer. Earlier this year, researchers studying dietary effects on humans went so far as to claim that calorie restriction may be more effective than exercise at preventing age-related diseases.

Needless to say, reduced caloric intake has its drawbacks. For one thing, you look like Nicole Richie. The other drawback is that you stop having sex, and not only because you look like Nicole Richie. As the Times notes:

Experts theorize that limited access to energy alarms the body, so to speak, activating a cascade of biochemical signals that tell each cell to direct energy away from reproductive functions, toward repair and maintenance.

From the perspective of your cells, the tradeoff is simple: when food is scarce, self-preservation becomes everything. All the luxuries of life - like sex and reproduction - become secondary, and your body just focuses on mere survival. (This also means that when our cells are well fed, they aren't that interested in maximizing our longevity. Evolution cares about offspring, not lengthy retirements. From the perspective of biology, the golden years are frivolous.)

Of course, all this research comes with a massive caveat: since 40 percent of Americans are currently obese, mass starvation probably isn't a viable public health plan. (If you want to learn more about resveratrol, a substance in red wine that seems to trigger the same biochemical pathway as caloric reduction, read the WSJ article. Several studies are now seeing if resveratrol can trick your cells into thinking they are starving.)