Appetite at "high altitude" [Operation Everest III (Comex-'97)]: a simulated ascent of Mount Everest

We hypothesized that progressive loss of body mass during high-altitude soj ourns is largely caused by decreased food intake, possibly due to hypobaric hypoxia. Therefore we assessed the effect of Long-term hypobaric hypoxia p er se on appetite in eight men who were exposed to a 31-day simulated stay at several altitudes up to the peak of Mt. Everest (8,848 m). Palatable foo d was provided ad libitum, and stresses such as cold exposure and exercise were avoided. At each altitude, body mass, energy, and macronutrient intake were measured; attitude toward eating and appetite profiles during and bet ween meals were assessed by using questionnaires. Body mass reduction of an average of 5 +/- 2 kg was mainly due to a reduction in energy intake of 4. 2 +/- 2 MJ/day (P < 0.01). At 5,000- and 6,000-m altitudes, subjects had ha rdly any acute mountain sickness symptoms and meal size reductions (P < 0.0 1) were related to a more rapid increase in satiety (P < 0.01). Meal freque ncy was increased from 4 +/- 1 to 7 +/- 1 eating occasions per day (P < 0.0 1). At 7,000 m, when acute mountain sickness symptoms were present, uncoupl ing between hunger and desire to eat occurred and prevented a food intake n ecessary to meet energy balance requirements. On recovery, body mass was re stored up to 63% after 4 days; this suggests physiological fluid retention with the return to sea level. We conclude that exposure to hypobaric hypoxi a per se appeals to be associated with a change in the attitude toward eati ng and with a decreased appetite and food intake.