Effects of overfeeding and underfeeding on energy expenditure and subsequent voluntary energy intake in normal-weight young men
1992
Roberts, S.B. | Heyman, M.B. | Fuss, P. | Evans, W.J. | Young, V.R.
We investigated the mechanisms of body weight regulation in young men of normal body weight leading unrestricted lives. Changes in total and resting energy expenditure, body composition, and subsequent voluntary nutrient intake in response to overeating by 1011 +/- 275 kcal per day (mean +/- SE) or undereating by 806 +/- 162 kcal per day for 21 days were measured in 14 subjects consuming a typical diet. On average, 85% to 90% of the excess energy intake during overeating was deposited, and there was no detectable difference between individuals in susceptibility to energy deposition. During underfeeding, body energy mobilization compensated for an average of 63% of the energy deficit. The resting metabolic rate, averaged for fasting and fed states, increased during overfeeding (+150 +/- 47 kcal/d, P < 0.01) and decreased during underfeeding (100 +/- 29 kcal/d, P < 0.01), but at least some of these amounts were due to changes in the obligatory expenditure associated with nutrient assimilation. No significant change in energy expenditure for physical activity or thermoregulation resulted from overfeeding or underfeeding. Thus energy expenditure did not substantially adapt to an increase or a decrease in energy intake. However, significant adaptation occurred in subsequent voluntary, energy intake, which promoted a rapid normalization of body weight. These findings indicate that adaptive changes in nutrient intakes are quantitatively more important than adaptive changes in energy expenditure in the regulation of energy balance in normal-weight men.
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