Many experiments have demonstrated that eating about 30 percent less than needed to keep up with the body’s energy needs extends longevity and improves health in animals ranging from the humble earthworm to rhesus monkeys. Humans who try calorie restriction appear to reduce their risk of heart disease and diabetes, and improve their immune function. There’s even some evidence that calorie restriction reduces the risk of Alzheimer’s disease -- in mice and monkeys, at least.














