Aging is a time-dependent, deleterious process known to be influenced by multiple factors and processes. Recent gerontological investigations have clearly shown nutrition to be the most powerful extrinsic factor influencing the aging process. That role has been clarified by recent inquiries on such underfeeding paradigms as calorie restriction. The idea of reduced calorie intake as a potent aging modulator contrasts dramatically with the traditional view that "more is better" which springs from the consideration of nutrition only as a source of energy and nutrients required to maintain health. This review presents pertinent data on how nutrition may influence the longevity of organisms and modulate age-related diseases.