Hypobaric hypoxia causes body weight reduction in obese subjects

Area of Science:

• Physiology
• Altitude Medicine
• Obesity Research

Background:

• The causes of weight loss at high altitudes remain unclear, with difficulty distinguishing effects of hypobaric hypoxia from increased physical activity.
• Previous studies have not isolated the impact of reduced oxygen availability on body weight.

Purpose of the Study:

• To investigate the specific effect of hypobaric hypoxia on body weight in obese subjects at high altitude.
• To differentiate the impact of altitude on weight from exercise-induced changes.

Main Methods:

• Twenty obese males underwent assessments at low altitude, high altitude (2,650 m), and post-return.
• Measurements included body weight, waist circumference, basal metabolic rate (BMR), activity, nutrition, blood gases, leptin, and ghrelin.
• Objective activity parameters were monitored to control for exercise effects.

Main Results:

• Participants experienced significant weight loss and increased BMR at high altitude and post-return, despite stable daily activity.
• Food intake decreased during the high-altitude stay.
• Leptin levels rose, and diastolic blood pressure decreased significantly at high altitude and post-return.

Conclusions:

• Obese individuals lose weight at high altitudes, attributed to increased metabolic rate and reduced food intake.
• Hypobaric hypoxia appears to be a significant factor, though mechanisms require further elucidation.
• Weight loss at high altitude correlated with clinically relevant improvements in diastolic blood pressure.