Effects of age on energy balance.

The effects of aging on energy requirements and energy balance have been studied by several research groups using the doubly labeled water method. The weight of evidence from these investigations suggests that current recommended dietary allowances underestimate the usual energy needs of adults of all ages, including older adults. In addition, doubly labeled water studies have found a significant negative association between body fatness and energy expenditure for physical activity, and a significant positive association between energy expenditure for physical activity and fat-free mass. Further studies are needed to refine estimates of energy requirements for different population groups and to address the role of physical activity in the prevention and treatment of obesity.