Regulation of energy expenditure in aging humans.

The regulation of daily energy expenditure and its components in aging humans in considered in this review. Specifically, the effects of age on resting metabolic rate (RMR), the thermic effect of a meal, body composition, and the interaction of these variables with physical activity in both men and women are considered. The possible modulators of the age-related decline in RMR are examined by exploring the influence of alterations in body composition, physical activity, and the sodium-potassium pump. Thereafter, the status of energy requirements in healthy and diseased individuals is examined. New information is presented regarding the use of the doubly-labeled water technique to measure daily energy expenditure and its applicability to the determination of daily energy requirements in free-living older persons.