A high whey protein-, leucine-, and vitamin D-enriched supplement preserves muscle mass during intentional weight loss in obese older adults: a double-blind randomized controlled trial.

BACKGROUND: Intentional weight loss in obese older adults is a risk factor for muscle loss and sarcopenia. OBJECTIVE: The objective was to examine the effect of a high whey protein-, leucine-, and vitamin D-enriched supplement on muscle mass preservation during intentional weight loss in obese older adults. DESIGN: We included 80 obese older adults in a double-blind randomized controlled trial. During a 13-wk weight loss program, all subjects followed a hypocaloric diet (-600 kcal/d) and performed resistance training 3×/wk. Subjects were randomly allocated to a high whey protein-, leucine-, and vitamin D-enriched supplement including a mix of other macro- and micronutrients (150 kcal, 21 g protein; 10×/wk, intervention group) or an isocaloric control. The primary outcome was change in appendicular muscle mass. The secondary outcomes were body composition, handgrip strength, and physical performance. Data were analyzed by using ANCOVA and mixed linear models with sex and baseline value as covariates. RESULTS: At baseline, mean ± SD age was 63 ± 5.6 y, and body mass index (in kg/m(2)) was 33 ± 4.4. During the trial, protein intake was 1.11 ± 0.28 g · kg body weight(-1) · d(-1) in the intervention group compared with 0.85 ± 0.24 g · kg body weight(-1) · d(-1) in the control group (P < 0.001). Both intervention and control groups decreased in body weight (-3.4 ± 3.6 kg and -2.8 ± 2.8 kg; both P < 0.001) and fat mass (-3.2 ± 3.1 kg and -2.5 ± 2.4 kg; both P < 0.001), with no differences between groups. The 13-wk change in appendicular muscle mass, however, was different in the intervention and control groups [+0.4 ± 1.2 kg and -0.5 ± 2.1 kg, respectively; ß = 0.95 kg (95% CI: 0.09, 1.81); P = 0.03]. Muscle strength and function improved over time without significant differences between groups. CONCLUSION: A high whey protein-, leucine-, and vitamin D-enriched supplement compared with isocaloric control preserves appendicular muscle mass in obese older adults during a hypocaloric diet and resistance exercise program and might therefore reduce the risk of sarcopenia. This trial was registered at the Dutch Trial Register (http://www.trialregister.nl) as NTR2751.