Caloric restriction and longevity: the science and the ascetic experience.

Aging involves a gradual increase in disorder of the systems that sustain living. Although stress is a major driver of this process, one stressor, caloric restriction (CR), is the only intervention proven to extend life span in multiple species as well as extend the persistence of those characteristics that are associated with youth. CR has been used since ancient times to enhance many of those characteristics: principally, increased activity levels and heightened levels of mental acuity.