Operation Everest II: Nutrition and Body Composition.

Progressive body weight loss occurs during high mountain expeditions, but whether it is due to hypoxia, inadequate diet, malabsorption, or to multiple stresses of the harsh environment is unknown. To determine whether hypoxia alone causes such weight loss, six men, provided with a palatable adlibitum diet, were studied during progressive decompression to 240 Torr for 40 days in a hypobaric chamber where hypoxia was the major variable. Caloric intake decreased 42.3 from 3136 kcal to 1789 kcal. The percent carbohydrate in the diet decreased from 62.1 to 53.2. All subjects lost weight averaging about 7.4 or - 2.2 kg. Hydrostatic weighing indicated that 4 subjects lost 2.7 body fat whereas two gained 0.65. Computerized tomographic scans indicated that most of the weight loss was derived from lean body mass. Data indicated that prolonged exposure to increasing hypoxia is associated with reduction in carbohydrate preference and body weight despite access to ample varieties and quantities of food. This study suggested that hypobaric hypoxia rather than the combined stress of the mountain environment is sufficient cause for the deteriorations in food consumption reported by mountain expeditions at high altitude. Keywords Acclimatization, Nutrition, Food Intake, Body composition.