Legacy effects of short-term intentional weight loss on total body and thigh composition in overweight and obese older adults

OBJECTIVE: Weight regain following intentional weight loss may negatively impact body composition, accelerating fat regain and increasing risk of physical disability. The purpose of this study was to compare long-term changes in whole body and thigh composition in obese older adults who intentionally lost and then partially regained weight to obese older adults who remained weight stable. SUBJECTS/METHODS: This pilot study analyzed total body (dual-energy X-ray absorptiometry (DXA)) and thigh (computed tomography (CT)) composition data collected from 24 older (65-79 years) adults 18 months after completion of a 5-month randomized trial that compared resistance training alone (RT) with RT plus caloric restriction (RT+CR). RESULTS: Mean loss of body mass in the RT+CR group (n=13) was 7.1 +/- 2.4 kg during the 5-month intervention (74% fat mass; 26% lean mass; all P < 0.01), whereas RT (n=11) remained weight stable (+0.3 +/- 1.8 kg; P=0.64). Differential group effects were observed for all DXA and CT body composition measures at 5 months (all P <= 0.01); however, by 23 months, group differences persisted only for total body (RT+CR: 81.6 +/- 10.0 kg vs RT: 88.5 +/- 14.9 kg; P=0.03) and lean (RT+CR: 50.8 +/- 9.3 kg vs RT: 54.4 +/- 12.0 kg; P < 0.01) mass. All RT+CR participants regained weight from 5 to 23 months (mean gain = +4.8 +/- 2.6 kg; P < 0.01). Total fat mass and all thigh fat volumes increased, whereas thigh muscle volume decreased, during the postintervention follow-up in RT+CR (all P <= 0.01). In the RT group, body mass did not change from 5 to 23 months (-0.2 +/- 0.9 kg; P=0.87). Decreased total thigh volume, driven by the loss of thigh muscle volume, were the only postintervention body composition changes observed in the RT group (both P < 0.04). CONCLUSIONS: Short-term body composition benefits of an RT+CR intervention may be lost within 18 months after completion of the intervention.