Weight Loss, Exercise, or Both and Physical Function in Obese Older Adults

Abstract

Obesity exacerbates the decline in physical function and frailty associated with aging and is an important cause of disability in older adults. A large number of studies have demonstrated the benefits of exercise and weight loss for people of all ages, but few studies have clearly defined the benefits of weight loss in older adults or the benefit of combined diet and exercise. This randomized controlled trial examined the effects of exercise, weight loss, or both in 107 obese adults 65 years of age or older. In this 1-year study, participants were randomly assigned to 1 of 4 following groups: a control group, a diet-only group, an exercise-only group, and a group that underwent both weight-management and exercise training (diet-exercise group). Increased scores from baseline values on the modified Physical Performance Test (the primary outcome) indicated better physical status. Similarly, increased scores on the Functional Status Questionnaire indicated reduced frailty (a secondary outcome), which also was assessed by measurement of peak oxygen consumption. Other secondary outcomes examined included body composition (lean body mass), bone mineral density of the hip, and specific physical functions (strength, balance, and gait). Of the 107 volunteers who underwent randomization, 93 (87%) completed the study. The scores on the Physical Performance Test increased more in the diet-exercise group (21%) than in the diet group (12%), the exercise group (15%), or the control group (1%); P < 0.001 for between-group differences. The peak oxygen consumption increased more in the diet-exercise group (17%) in comparison with the diet group (10%) or the exercise group (8%), P < 0.001 for both comparisons. The Functional Status Questionnaire scores increased more in the diet-exercise group compared with the diet group (10% vs. 4%, respectively). A substantial decrease from baseline in body weight was observed in the diet group (9.7% decrease) and in the diet-exercise group (9% decrease), but not in the exercise group (1% decrease) or the control group (<1% decrease); P < 0.001. Lean body mass decreased less in the diet-exercise group (3% reduction from baseline) than in the diet group (a 5% reduction from baseline); P < 0.05. Bone mineral density at the total hip also decreased less in the diet-exercise group (1.1% decrease from baseline) compared with the diet group (2.6% decrease from baseline); P < 0.05. There was a consistent improvement in specific physical functions (strength, balance, and gait) in the diet-exercise group (P < 0.05 for all 3 comparisons). The findings suggest that, individually, diet and exercise improve physical performance, but the benefits of combined diet-exercise are considerably better than each intervention alone.