Effects of whey protein supplementation on dietary compensation and muscle energetics in elderly adults

Abstract

PurposeThis study assessed the effects of whey protein (WPro) supplementation on dietary compensation (DC) and skeletal muscle gross mechanical efficiency (GME), an index of muscle energetics, in elderly people.MethodsUsing a randomized, crossover design, 12 adults (7 F, 5 M), aged 82 ± 7 y (mean ± SD) completed two 6‐day periods of consuming fruit‐smoothie beverages twice daily (with breakfast and lunch) containing 230 kcal and 25 g WPro or 25 g corn‐derived glucose polymer (CHO) (total 460 kcal/d and 50 g/day WPro or CHO). On day 7 of each period, GME was measured while the subjects were fasting and exercising on a stationary cycle at 1, 10, and 20 watts.ResultsCompared with baseline, total energy intake was ~286 kcal/d higher during WPro and CHO, consistent with incomplete DC to the supplements (~36–40% DC). Total protein intake was 46 ± 13 g/d higher with WPro vs. CHO. During exercise, GME was progressively higher from 1 to 10 to 20 watts. Compared to baseline, GME was not different for WPro or CHO. Among all subjects, the magnitude of DC did not influence the change in GME at 1, 10, or 20 watts.ConclusionFor elderly adults, short‐term use of supplements with whey protein or glucose polymer effectively increase total energy intake due to incomplete dietary compensation. These dietary changes did not influence muscle energetics during low‐level physical activity.Support: NIH CTSI Grant #TR000006