Moderate exercise attenuates the loss of skeletal muscle mass that occurs with intentional caloric restriction-induced weight loss in older, overweight to obese adults

Abstract

Background. Aging is associated with a loss of muscle mass and increased body fat. The effects of diet-induced weight loss on muscle mass in older adults are not clear. Purpose. This study examined the effects of diet-induced weight loss, alone and in combination with moderate aerobic exercise, on skeletal muscle mass in older adults. Methods. Twenty-nine overweight to obese (body mass index = 31.8 ± 3.3 kg/m2) older (67.2 ± 4.2 years) men(n = 13) and women(n = 16) completed a 4-month intervention consisting of diet-induced weight loss alone (WL; n = 11) or with exercise (WL/EX; n = 18). The WL intervention consisted of a low-fat, 500-1,000 kcal/d caloric restriction. The WL/EX intervention included the WL intervention with the addition of aerobic exercise, moderate-intensity walking, three to five times per week for 35-45 minutes per session. Whole-body dual-energy x-ray absorptiometry, thigh computed tomography (CT), and percutaneous muscle biopsy were performed to assess changes in skeletal muscle mass at the whole-body, regional, and cellular level, respectively. Results. Mixed analysis of variance demonstrated that both groups had similar decreases in bodyweight (WL,-9.2% ± 1.0%; WL/EX,-9.1% ± 1.0%) and whole-body fat mass (WL,-16.5%, WL/EX,-20.7%). However, whole-body fat-free mass decreased significantly(p