A comparison of resting metabolic rate, self-rated food intake, growth hormone, and insulin levels in obese and nonobese preadolescents

The objective was to investigate metabolic (resting metabolic rate), behavioral (energy intake), and endocrine variables (fasting insulin and growth hormone levels) potentially responsible for a positive energy balance in obese children in a cross-sectional study. The study was in 25 obese children aged 8 to 12 years and 21 nonobese children of the same age range. Weight, height, lean body mass (LBM) and fatmass (FM) were measured by bioelectrical impedance analysis, resting metabolic rate (indirect calorimetry) for the duration of 25 min, 7-day food records and fasting levels of insulin and human growth hormone (HGH). In the total sample, no differences were found in resting metabolic rate (RMR controlled for differences in weight) and energy intake between groups, whereas fasting insulin level was significantly higher and basal growth hormone concentration was significantly lower in the obese children. In RMR, there were significant age-dependent differences only in 10-year-old children, with the obese subjects showing lower values. The results fit in a multidimensional model, taking into account a critical period in prepubertal age for the development of childhood obesity. This period may be characterized by a reduced RMR, which results in an increased body weight, even if there is no excessive energy intake. (C) 1997 Elsevier Science Inc.