I was bowled over by this so-called calorie-restriction diet that some people are on to prolong their individual life spans. Newsweek has an article on its latest issue. Apparently, food-deprived rats lived longer and looked younger than those that ate normally.
The effect has been seen in animals from fruit flies to roundworms to mice: reduce food intake by roughly a third, while maintaining adequate nutrition, and life span goes up by about 30 percent.
So some people are trying it as well. How is this calorie restriction supposed to work to humans? Here's one theory:
... calorie restriction slows metabolism, the burning of glucose for energy. This effect—which presumably serves the evolutionary purpose of conserving calories during periods of famine—is well known to dieters; as they eat less, their metabolic rate drops, and it becomes progressively harder to burn off fat. It's clear that metabolism slows in people on CR regimens; in one study, core body temperature dropped by one full degree. Metabolism, an essential life process, is also a destructive one; it produces free radicals, unstable molecules that can damage the structures of living cells by the process known as oxidation. Antioxidant vitamins and supplements ranging from vitamin C to green-tea extracts have been the rage for decades, though there is little evidence that they have any effect on longevity; calorie-restriction diets reduce oxygenating compounds at their source—a plausible, if equally unproved, mechanism for extending life.