LONGITUDINAL CHANGES IN FATNESS IN WHITE-CHILDREN - NO EFFECT OF CHILDHOOD ENERGY-EXPENDITURE

Reduced energy expenditure may predispose children to the development of obesity, but there are limited longitudinal studies to support this theory. We studied 75 white, preadolescent children over 4 y by takin g annual measures of body composition and resting energy expenditure ( by indirect calorimetry) and two annual measures of total energy expen diture and physical-activity-related energy expenditure (by doubly lab eled water). Body composition of parents was assessed at the onset of the study with use of underwater weighing. The major outcome variable was the individual rate of change in fat mass (FM) adjusted for fat-fr ee mass (FFM). The influence of sex, energy expenditure components, in itial FM, and parental FM on the rate of change in FM was analyzed by hierarchical linear modeling and analysis of variance. The rate of cha nge in absolute FM was 0.89 +/- 1.08 kg/y (range: -0.44 to 5.6 kg/y). The rate of change in FM adjusted for FFM was 0.08 +/- 0.64 kg/y (rang e: -1.45 to 2.22 kg/y) and was similar among children of two nonobese parents and children with one nonobese or one obese parent, but was si gnificantly higher in children with two obese parents (0.61 +/- 0.87 k g/y). The major determinants of change in Fh I adjusted for FFM were s ex (greater fat gain in girls), initial fatness, and parental fatness. None of the components of energy expenditure were inversely related t o change in FM. The main predictors of change in FM relative to FFM du ring preadolescent growth are sex, initial fatness, and parental fatne ss, but not reduced energy expenditure.