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Weight loss and changes in body composition at high altitude
Summary
Extreme altitude causes significant weight loss in Caucasians due to muscle breakdown and malabsorption, while Sherpas show greater resilience. Body fat percentage does not prevent muscle loss at high altitudes.
Area of Science:
- Human Physiology
- Altitude Medicine
- Body Composition Research
Background:
- Understanding physiological adaptations to extreme altitude is crucial for mountaineers and researchers.
- Previous studies have limited data on weight loss and body composition changes at high altitudes.
Purpose of the Study:
- To investigate weight loss and body composition changes in Caucasian and Sherpa individuals at extreme altitudes.
- To assess the impact of altitude on fat absorption and nutrient utilization.
Main Methods:
- Measurements included body weight, body fat percentage, limb circumferences, dietary intake, stool fat, and urine xylose excretion.
- Data collected from Caucasian and Sherpa members of the 1981 American Medical Research Expedition to Everest at various altitudes.
Main Results:
- Caucasians experienced significant weight loss, with muscle catabolism contributing more at higher altitudes (>5,400 m).
- Sherpas, with lower initial body fat, maintained weight and limb circumferences at extreme altitudes.
- Reduced fat absorption and xylose excretion indicated malabsorption at 6,300 m.
Conclusions:
- Muscle catabolism and malabsorption are significant factors in high-altitude weight loss.
- Higher initial body fat does not protect against muscle tissue loss at extreme altitudes.
- Sherpas exhibit distinct physiological resilience to high-altitude conditions compared to Caucasians.