A Research Agenda: The Changing Relationship Between Body Weight and Health in Aging

IT is increasingly recognized that changes in weight and body composition with age are strongly connected with health status and physical function. Aging is typically associated with reductions in total and lean mass, so that in the last few years of life, older people frequently report having lost weight and strength (1–3). We know only a few important facts about this process. On average, muscle mass declines with age, and even in older persons with stable weight, muscle is replaced by fat over time (4,5). Increasing fatty infiltration of muscle tissue is associated with decreasing muscle strength (6). The general pattern of weight change over the lifetime is that weight increases through approximately age 60 years and decreases thereafter (7). Weight gain from early adulthood through midlife is related to increases in both fat and muscle mass, but weight loss at older ages is associated with higher risk for a disproportionate decline in muscle mass (1,8).