Abstract
Altitude exposure may suppress appetite and hence provide a viable weight-loss strategy. While changes in food intake and availability as well as physical activity may contribute to altered appetite at altitude, herein we aimed to investigate the isolated effects of hypobaric hypoxia on appetite regulation and sensation. Twelve healthy women (age: 24.0±4.2 years, body mass: 60.6±7.0 kg) completed two 4-day sojourn in a hypobaric chamber, one in normoxia (PB=761 mmHg, 262 m, NX) and one in hypobaric hypoxia (PB=493 mmHg, HH) equivalent to 3,500 m altitude. Energy intake was standardized 4 days prior and throughout both sojourns. Plasma concentrations of leptin, acylated ghrelin, cholecystokinin (CCK) and cytokine growth differentiation factor 15 (GDF15) were determined every morning. Before and after breakfast, lunch and dinner, appetite was assessed using visual analogue scales. Body mass was significantly decreased following HH but not NX (-0.71±0.32 kg vs. -0.05±0.54 kg, condition: p<0.001). Compared to NX, acylated ghrelin decreased throughout the HH sojourn (condition x time: p=0.020), while leptin was higher throughout the entire HH sojourn (condition: p<0.001). No differences were observed in CCK and GDF15 between the sojourns. Feelings of satiety and fullness were higher (condition: p<0.001 and p=0.013, respectively), whereas prospective food consumption was lower in HH than in NX (condition: p<0.001). Our findings suggest that hypoxia exerts an anorexigenic effect on appetite regulating hormones, suppresses subjective appetite sensation and can induce weight loss in young healthy women. Among the investigated hormones, acylated ghrelin and leptin most likely explain the observed HH-induced appetite suppression.