A look at present human studies of the health benefits of calorie restriction at the New York Times: "As Americans become fatter and fatter - a study published in July revealed that obesity rates increased in 23 states last year and declined in none - a select group of men and women under the watchful care of medical professionals have spent the past few years becoming thinner and thinner. There are 132 of them, located in and around Boston, St. Louis and Baton Rouge, La. All are enrolled in a large clinical trial that is financed by the National Institutes of Health and known as Calerie, which stands for Comprehensive Assessment of Long-Term Effects of Reducing Intake of Energy. ... the Calerie project [is] that it is not meant to study weight loss or if one type of diet is better than another. Instead, Calerie is investigating how (and if) a spartan diet affects the aging process and its associated diseases. To the Calerie researchers, these are quite distinct. The aging process, which researchers sometimes call 'primary' or 'intrinsic' aging, refers to the damage that ordinarily accumulates in our cells as we grow older, a natural condition that seems to have limited the maximal lifespan of humans to 120 years. Diseases that accompany the aging process - often called 'secondary aging' - are those afflictions increasingly prevalent in the elderly, like cancer, diabetes and cardiovascular disease."