[Energy expenditure and obesity]

Abstract

This analysis of the literature examines available data on energy expenditure in human obesity, with the purpose of evaluating whether deficient energy expenditure can contribute to excess body weight. The most significant informations are the following: 1) considerable inaccuracy in self-reports of energy intake has been documented with systematic underreporting in obese patients (up to 50%). This precludes the use of this source of information for the indirect evaluation of energy expenditure; 2) measurement of energy expenditure itself indicates that obesity is associated with an increased basal metabolic rate and elevated rates of 24-h energy expenditure in proportion to excess body weight; 3) a negative caloric balance induced by food restriction reduces energy expenditure but post-obese patients maintained at constant body weight have normal metabolic rates; 4) during experimental overfeeding, the energy cost of induced weight gain is not reduced in obese patients. Thus, contrary to many patient's belief, there are no scientific arguments in favour of the existence of a "metabolic" type of obesity in which excess body weight would result from a deficiency in energy expenditure rather than from an excessive caloric intake.