Body composition, resting metabolic rate, and energy requirements of short- and normal-stature, low-income Guatemalan children.

We examined body composition using bioelectrical impedance analysis and isotope dilution (18O and 2H), resting metabolic rate (RMR) by indirect calorimetry, and total energy expenditure (TEE) by doubly labeled water in 15 short-stature (height-for-age < or = -1.5 SD) and 15 normal-stature (height-for-age > -1.5 SD) Guatemalan children aged 4-6 y. Although, in absolute terms significant group differences were found in fat-free mass (FFM), fat mass, and total body water (TBW), there were no significant differences in fat mass and TBW after adjustment for FFM. RMR of the short-stature children (3791 +/- 376 kJ/d) was not significantly different from that of normal-stature children (4038 +/- 531 kJ/d), and the regression between RMR and FFM was also not significantly different between groups. TEE was not significantly different in short-stature (4753 +/- 761 kJ/d) compared with normal-stature children (5304 +/- 1020 kJ/d); the regression between TEE and FFM was not significantly different between the two groups. There were no significant group differences in RMR and TEE after adjustment for FFM. FFM was the strongest predictor of TEE, but could only explain 29% of the variance. We conclude that 1) the lower TBW and fat mass in the short-stature group is proportional to their lower FFM, 2) there is no significant difference in either RMR or TEE between short- and normal-stature children, and 3) TEE is highly variable among these children and cannot be explained by differences in body size alone.