Loss of
body weight and fat-free mass (FFM) are commonly noted with prolonged exposure to hypobaric
hypoxia. Recent evidence suggests
protein supplementation, specifically
leucine, may potentially attenuate loss of FFM in subcaloric conditions during normoxia. The purpose of this study was to determine if
leucine supplementation would prevent the loss of FFM in subcaloric conditions during prolonged
hypoxia. Eighteen physically active male (n = 10) and female (n = 8) trekkers completed a 13-day trek in Nepal to Everest Base Camp with a mean altitude of 4140 m (range 2810-5364 m). In this double-blind study, participants were randomized to ingest either
leucine (LEU) (7 g
leucine, 93 kcal, 14.5 g whey-based
protein) or an isocaloric isonitrogenous control (CON) (0.3 g LEU, 93 kcal, 11.3 g
collagen protein) twice daily prior to meals.
Body weight, body composition, and circumferences of bicep, thigh, and calf were measured pre- and post-trek. There was a significant time effect for
body weight (-2.2% ± 1.7%), FFM (-1.7% ± 1.5%), fat mass (-4.0% ± 6.9%), and circumferences (p < 0.05). However, there was no treatment effect on
body weight (CON -2.3 ± 2.0%; LEU -2.2 ± 1.5%), FFM (CON -2.1 ± 1.5%; LEU -1.2 ± 1.6%), fat mass (CON -2.9% ± 5.9%; LEU -5.4% ± 8.1%), or circumferences. Although a significant loss of
body weight, FFM, and fat mass was noted in 13 days of high altitude exposure, FFM loss was not attenuated by
leucine. Future studies are needed to determine if
leucine attenuates loss of FFM with longer duration high altitude exposure.