Moderate protein intake improves change in lean to fat ratio after 1 year of weight loss in adults

Abstract

Higher protein intake may attenuate loss of lean soft tissue (LST) in relation to fat mass (FM) during weight loss. This study assessed body composition changes during weight loss and maintenance using a moderate protein intake (PRO) vs. a traditional high carbohydrate diet (CARB). Overweight (N=130, BMI=32.5±0.5 kg/m2) middle‐aged subjects [59 male (M), 71 female (F)] were randomized to energy‐restricted (deficit ~500 kcal/d) diets providing protein at 1.6 g.kg−1.d−1 (PRO) or 0.8 g.kg−1.d−1 (CARB). LST and FM were measured using dual X‐ray absorptiometry. LST:FM ratio and percent change in this ratio from baseline were tested in a repeated measures ANOVA controlling for gender, study site, and their interactions with time and diet at 0, 4, 8 and 12 mo. PRO subjects lost more weight (−16.5±1.5 vs. −12.3±0.9 kg; P<0.01) and fat (−11.7±1.0 vs. −7.9±0.7 kg; P<0.01) than CARB. Ratios did not differ at time points. By 12 mo the model estimated change in LST:FM ratio was greater in PRO (M: 2.04, 95%CI: 1.90–2.21; F: 1.87, 95%CI: 1.76–1.99) vs. CARB (M: 1.93, 1.80–2.09; F: 1.84, 1.73–1.97), P=0.027 for group × time interaction. Similarly, LST:FM percent change from baseline was higher in PRO (M: 24.5%, 14.8–40.6; F: 11.1%, 7.0–17.5) vs. CARB (M: 17.4%, 10.2–29.8; F: 7.60%, 4.6–12.6), P=0.012 for group × time interaction. PRO was more effective in maintaining LST in relation to FM vs. CARB over 12 mo weight loss and maintenance.