Long-term change in body composition following intentional weight loss and its effect on physical function

Background/Objectives: A concern with intentional weight loss among middle-aged and older adults with obesity and type 2 diabetes mellitus (T2DM) is the loss of lean mass, which may lead to declining physical function. However, the association between changes in body composition with intentional weight loss and physical function over the long-term is unknown. Thus, we examined the association between changes in body composition and physical function 8 years following an intensive lifestyle intervention (ILI). Subjects/Methods: We conducted a secondary analysis of participants at the Baton Rouge site within the Look AHEAD study. Participants (n = 220) were middle-aged and older adults with overweight/obesity and T2DM randomized to an ILI or diabetes support and education (DSE). Body composition was measured by dual-energy X-ray absorptiometry at baseline and Year 8. Physical performance (expanded Short Physical Performance Battery [SPPB_exp], 20- and 400-m walk) and strength (grip and knee extensor) were assessed at Year 8. Results: Percent change (mean ± SD) from baseline in weight, fat and lean mass over 8 years were −4.0 ± 7.3%, 0.2 ± 12.5% and −6.5 ± 5.3% in ILI and −3.0 ± 9.7%, 1.2 ± 17.1% and −5.8 ± 6.6% in DSE, respectively. ILI had better SPPB_exp scores and faster gait speed than DSE at 8-year follow-up (p < 0.05). Increases in fat mass were associated with worse SPPB_exp scores in ILI and DSE (p = 0.03) and with slower gait speed in DSE (p = 0.01). Decreases in lean mass were associated with weaker grip strength in ILI (p = 0.04) and knee extensor strength in ILI and DSE (p < 0.05). There were no significant interactions by intervention group. Conclusions: Although the overall intervention effect on physical function was positive, increases in fat mass were associated with poorer physical performance while lean mass loss was associated with weaker strength 8 years post-randomization. Findings highlight the importance of minimizing fat mass gain/regain and loss of lean mass during intentional weight loss.