A mainstream article on calorie restriction from the Houston Press: "More than 1,000 studies dating back 70 years have shown that eating less, a lot less, retards the aging process and boosts health in a wide variety of laboratory animals: fruit flies, spiders, nematodes, mice, rats, dogs and rhesus monkeys. Calorie-restricted monkeys, for instance, look less wrinkled as they age. They have less gray hair, and look and act younger than their regular-diet counterparts. Eating less seems to make the metabolic processes in the body work more efficiently ... The body enters an altered state that puts the brakes on aging. In mice, flies and monkeys, that is. ... Calorie restriction works in the lower organisms, we know. But with humans it's anybody's guess so far. ... The best guess in the scientific community is that starting a program of calorie restriction in your thirties might add two years ... If you start in your forties, it's six months. Start later than that, it's negligible. It could be a few extra weeks." Longevity benefits are currently thought to be minimal, but the health benefits in humans - in terms of resisting age-related disease, for example - are demonstrated to be large whenever you start.