ABSTRACT
The anti-aging action of food restriction may have a hormonal rather than nutritional basis. The physiological effects of undernutrition have been studied extensively in human subjects and are summarized in the monograph the biology of human starvation. Undernutrition by altering neurotransmitter metabolism in the hypothalamus reduces the secretion of releasing hormones and thence pituitary tropic and peripheral hormones; the lack of hormones then slows tissue aging. The relative contributions of the direct aging action of nutrients and metabolites on tissue cells and the indirect action via hypothalamic-pituitary complex are unknown. Food restriction has been shown to depress certain hypothalamic-pituitary functions leading to reduced pituitary hormone secretion. The food-restricted rat lives longer than its fullyfed control largely because of increased resistance to the diseases of old age. Compared with intact fully fed controls, both hypophysectomized and food restricted rats are remarkably free of pathological lesions except for respiratory disease which is common to all conventional rats.
