Impact of Body Composition on Physical Performance Tasks in Older Obese Women Undergoing a Moderate Weight Loss Program.

BACKGROUND: Although obesity is a recognized risk factor for impaired physical function in older adults, there is still debate on whether older obese adults should undergo intentional weight loss due to concern of loss in lean body mass, including appendicular lean soft tissue mass. This may put them at risk for worsening muscle strength and mobility.

OBJECTIVES: Therefore, the purpose of this study was to examine the effect of a weight loss intervention on body composition and physical function in obese older women.

DESIGN: Women were randomized into either a weight stable (WS) (n=20) or an intensive weight loss (WL) (n=26) group.

SETTING: The study setting was at a university research facility.

PARTICIPANTS: Women (age, 67.8±1.3 yrs; BMI, 34.9 (0.7) kg/m2; mean±standard error of the mean) were recruited.

INTERVENTION: The WL intervention was for 6 months and included moderate dietary energy restriction and aerobic and strength exercise training.

MEASUREMENTS: Variables were obtained at baseline and 6-months and included body weight, dual energy x-ray absorptiometry (DXA), 6-minute walk distance, stair climb time, and concentric knee extension muscular strength.

RESULTS: Estimated marginal means (SEM) for weight loss at 6-months was -8.5 (0.9)% for WL and +0.7 (1.0)% for WS. There was a significant loss of body fat mass, lean body mass, appendicular lean soft tissue mass, relative muscle mass, and skeletal muscle index for WL vs. WS at 6-months. However, improvements for WL vs. WS were seen in 6-minute walk distance and stair climb time, and trends for improved relative strength and leg muscle quality. Change in body fat mass was positively related to improved physical function and muscle strength and quality.

CONCLUSION: These results further support the use of a sound intentional weight loss program incorporating moderate dietary energy restriction and exercise training in older obese women to improve physical function. Although lean soft tissue mass was lost, over the 6-month program there was no deleterious effect on muscle strength or muscle quality.