Effect of Exercise Type during Intentional Weight Loss on Body Composition in Older Adults with Obesity

OBJECTIVE: To examine the long-term effects of exercise modality during weight loss on body composition and associations between body composition and physical function changes. METHODS: 249 older adults (66.9±4.7 years, 71% women, 32% African American, BMI: 34.4±3.7 kg/m(2)) were randomized to weight loss (WL; n=82), WL plus aerobic training (WL+AT; n=86), or WL plus resistance training (WL+RT; n=81) for 18-months. DXA-acquired body composition, 400-m walk time, and knee extensor strength were measured at baseline, 6-, and 18-months. RESULTS: Total body mass loss was enhanced when WL was combined with exercise (WL: −5.7±0.7 kg, WL+AT: −8.5±0.7 kg, WL+RT: −8.7±0.7 kg; p<0.01). Total body fat mass loss was significantly greater in WL+AT (−6.8±0.6 kg, −16.4%) and WL+RT (−7.8±0.5 kg, −19.0%) than WL (−4.8±0.6 kg, −10.9%); both p<0.01. Lean mass loss was greatest in WL+AT (−1.6±0.3 kg, −3.1%) compared to WL+RT (−0.8±0.3 kg, −1.5%) or WL (−1.0±0.3 kg; −2.0%); both p≤0.02). Change in 400-m walk time was associated with change in fat mass (β/SD=+6.1 sec; p<0.01), while change in knee extensor strength was associated with change in lean mass (β/SD=+1.6 Nm; p<0.01). CONCLUSIONS: WL+RT results in less lean mass lost than WL+AT; WL plus exercise yields greater fat mass loss than WL alone.