The role of resting energy expenditure (REE) in the development of obesity in children is controversial. Our aim was to test the hypothesis that REE has a meaningful impact on change in weight or body composition in healthy children. Resting energy expenditure by indirect calorimetry and body composition by dual-energy x-ray absorptiometry were measured in 236 children (131 boys) on 7 annual occasions (7-13 years). The effect of REE at 7 years on change in weight and body composition was analyzed using linear mixed effects models. In neither sex was there an interaction between REE at 7 years and change in weight (P > .9). There were weak associations between REE at 7 years and change in body composition in boys but not in girls: for a 418 kJ (100 kcal) lower REE at 7 years, an increase in rate of change in fat mass of approximately 0.1 kg/y and in percentage of fat of 0.2% per year and a decrease in fat-free mass of 0.1 kg/y. Change in REE during follow-up was not significantly associated with body composition changes in either sex (P > .06). Thus, REE has little impact on the wide variation in weight gain at this age; although in boys, some fat was simply exchanged for lean, the effect was small. Resting energy expenditure does not appear to provide an explanation for childhood obesity.
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