Body Weight, Body Composition, and Aging

Abstract

One of the fastest growing segments of the population is individuals >65 years of age. This age group, which currently accounts for ∼15% of the population, is expected to grow to between 19 and 25% by 2025. Increased body fat and loss of bone mineral density (BMD) and muscle mass are defining characteristics of the aging process. These changes in body composition occur as a result of normal aging, have a detrimental effect on health status, and have substantial economic consequences on the health care system. Obesity is associated with an increased prevalence of comorbidities, including cardiovascular disease, type 2 diabetes mellitus, hypertension, dyslipidemia, and other metabolic diseases. The decline in skeletal muscle mass is associated with weakness, functional disability, frailty, and morbidity, whereas the decrease in BMD increases the risk of bone fractures and ultimately results in high rates of disability, morbidity, and mortality in the elderly. This article discusses the classification and prevalence of overweight and obesity and the changes that occur during the aging process, with emphasis on body weight, fat mass, and fat-free mass and its constituents of skeletal muscle mass, total body water, and bone. These changes in body composition are also described in context with metabolic disease states.