Walford, a UCLA biomedical researcher, is an optimist with a plan: on the basis that there may be some truth in several current theories of aging, he's espousing a program that emphasizes under- but not malnutrition. Slowly, over a four- or five-year period, he proposes to drop his weight by 20 to 30 lbs., while maintaining a balanced diet supplemented by assorted vitamins and additives--not in megadoses and not in one gulp, but spaced over the day according to their metabolic rates and interactions. The rationale is a long-observed phenomenon: underfed but not malnourished animals age more slowly and live longer than littermates. That, and a dropping of body temperature, have both been associated with longevity; the cooling trick, however, is impractical for Homo sapiens. In the book's second half, Walford presents past and present theories of aging, tales of false leads and falser prophets. (Treks to Dr. Paul Niehan's posh Swiss clinic for the fetal lamb cell treatment are described as ""Gullibles Travels."") As Walford trots out popular theories on the causes of aging--DNA repair breakdown, immune defects, cross-links--he defends the additives he proposes by stating: ""Admittedly I am being selective in my citation of a vast and not always agreeing scientific literature, but most of the news is either good or neutral, quite like what Pascal said about the effects of prayer."" As added filips, he describes trips to India to see touted yogis; debunks assorted cures; and shoots down the longevity legends from remote parts of the world. A spirited update--take or leave the program.