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Operation Everest. II: Nutrition and body composition
M S Rose1, C S Houston, C S Fulco
1US Army Research Institute of Environmental Medicine, Natick, Massachusetts 01760.
Journal of Applied Physiology (Bethesda, Md. : 1985)
|December 1, 1988
Summary
Hypoxia, or low oxygen, causes significant weight loss and reduced food intake, even with ample food. This study demonstrates that reduced oxygen levels are a primary driver of weight loss during high-altitude expeditions.
Area of Science:
- Environmental Physiology
- Human Physiology
- Altitude Medicine
Background:
- High mountain expeditions are associated with progressive body weight loss.
- The exact causes, including hypoxia, diet, malabsorption, and environmental stress, remain unclear.
Purpose of the Study:
- To investigate whether hypoxia, independent of other factors, causes weight loss.
- To determine the impact of progressive decompression on caloric intake, dietary preference, and body weight.
Main Methods:
- Six healthy males were exposed to progressive decompression to 240 Torr over 40 days in a hypobaric chamber.
- A palatable ad libitum diet was provided, and caloric intake, dietary composition, and body weight were monitored.
- Computerized tomographic scans were used to assess body composition changes.
Main Results:
- Caloric intake decreased by 43.0% (from 3,136 to 1,789 kcal/day).
- Subjects lost an average of 7.4 kg, with most of the loss attributed to fat-free mass.
- A reduction in carbohydrate preference was observed alongside decreased body weight.
Conclusions:
- Hypoxia alone is sufficient to cause significant weight loss and reduced food consumption.
- These findings suggest hypoxia is a primary factor in the weight loss observed during high-altitude expeditions.