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Performance of normal-weight and underweight men with marginal changes in energy intake
S A Chiplonkar1, V V Agte, P V Sukhatme
1Department of Biometry and Nutrition, MACS Research Institute, Pune, India.
Nutrition (Burbank, Los Angeles County, Calif.)
|September 1, 1992
Summary
Underweight individuals exhibit a more pronounced metabolic rate reduction during underfeeding and a greater increase during overfeeding compared to normal-weight individuals. This suggests distinct metabolic adaptations to energy balance changes.
Area of Science:
- Human Physiology
- Metabolic Studies
- Nutritional Science
Background:
- Underweight (BMI < 18 kg/m2) and normal-weight (20 < BMI < 25) men differ in body composition and basal metabolic rate (BMR).
- Understanding metabolic responses to energy deficits and surpluses is crucial for managing body weight and metabolic health.
Purpose of the Study:
- To compare the continuous physiological responses of underweight and normal-weight men to sustained underfeeding and overfeeding.
- To assess changes in body weight, body composition, basal metabolic rate, and energy balance in response to altered energy intake.
Main Methods:
- Six underweight and six normal-weight men participated in a controlled study under metabolic-ward conditions.
- Subjects underwent periods of underfeeding (10% deficit) and overfeeding (10% surplus) for 4 weeks each, with a return to habitual intake in between.
- Measurements included habitual energy intake, body composition, basal metabolic rate, and body weight changes.
Main Results:
- Underweight subjects demonstrated a more rapid and significant reduction in BMR during the first week of underfeeding (13.4%) compared to normal-weight subjects (8.1%).
- Underweight individuals showed greater resistance to weight loss during underfeeding (mean loss 180g) versus normal-weight subjects (mean loss 730g).
- Overfeeding led to a higher mean increase in BMR for underweight subjects (7.4%) than for normal-weight subjects (5.3%).
Conclusions:
- Underweight individuals exhibit more pronounced and potentially adaptive changes in metabolic rate in response to energy balance perturbations.
- These findings highlight distinct metabolic flexibility between underweight and normal-weight individuals, impacting weight regulation and energy expenditure.