Assessment of energy requirements in elderly populations

The daily energy requirements of older adults are unclear. Aging results in a decline in daily energy expenditure and intake, which are associated with greater gains in body fatness and a subsequently higher risk of morbidity and mortality. Understanding the energy requirements of older populations, therefore, has important clinical implications. Current world-wide recommendations suggest that energy needs of individuals above 50 y are of 1.51 times resting energy expenditure. Limited data suggest that this may be an underestimation of energy needs in older Caucasian women and men. In contrast, current energy requirement recommendations may be appropriate for older African-American women, because of their low rate of daily energy expenditure for their metabolic size. Aging is also associated with Alzheimer's and Parkinson's and recent data suggest that individuals with these chronic diseases actually have energy requirements that are at or below current recommendations. Physical activity is the most modifiable and variable component of daily energy expenditure and, therefore, energy requirements. Current data suggest that an inexpensive and simple measurement of physical activity is difficult in older adults, which limits our ability to accurately determine energy needs. Overall, current data suggest that energy needs of older adults may be higher than current world-wide recommendations, although future prospective data are needed in healthy, ethnic, and diseased populations. Accurate, unobtrusive, and inexpensive methods to measure physical activity are also needed to assess energy requirements.