Protein supplementation during 6 mo weight loss enhances body composition changes in older women

Abstract

Adverse increases in adiposity and reductions in fat free mass (FFM) are age related changes in body composition and are linked to declines in physical function in older women. Higher protein intake in weight loss may augment fat mass (FM) loss and attenuate FFM loss, which may benefit function. This study assessed effects of 6 mo weight loss supplemented with powdered protein or placebo on body composition and function in older obese women. Women (63.8±3.4 yrs, BMI 32.9±4.1 kg/m2) were prescribed an energy‐restricted diet (1500 kcal/d; 15, 65, 30% of energy from protein, CHO and fat, respectively) and randomly assigned to 2 × 25g/d of whey protein (PRO, n=8) or maltodextrin (CARB, n=7) supplementation. Measures included whole body FM and FFM with DXA; thigh muscle, subcutaneous (SUBQ), intermuscular and intramyocellular fat with MRI; knee extension and flexion strength with isokinetic dynamometry. PRO trended towards greater weight loss (−10.6±6.7%, −5.0±4.0%; p=0.078), had greater reductions in FM (−18.9±10.6%, −8.0±4.2%; p=0.024) than CARB, but no significant difference in FFM (−4.0±4.9%, −2.0±4.1%; p=0.414). %SUBQ thigh fat change (−6.1±3.0%, −1.3±1.7%; p=0.003) was the only significant MRI outcome. Groups did not differ in leg strength changes. Higher protein intake in weight loss in older women enhances FM reductions while preserving FFM; however, these changes do not impact changes in physical function.Grant Funding Source: National Dairy Council, Carraway Foundation