Comparison of body fat calculations by sex and puberty status in obese schoolchildren using two and four compartment body composition models.

INTRODUCTION Determine body composition changes in adiposity can assess an individual. OBJECTIVE The objective of this study was to evaluate total body fat percentage based on two and four compartment models in obese Chilean school children, adjusting for differences in sex and puberty status. METHODS Sixty-one obese school children (33 boys and 28 girls) between 8 and 13 years of age were evaluated. Two compartment measurements of body fat percentage considered isotope dilution, plethysmography, radiographic absorptiometry and bioelectrical impedance; using the four compartment model as a benchmark. RESULTS Each method explained between 43-87% of the variance in body fat percentage in Tanner stage I and II children and between 78-96% in Tanner stage III and V children. In both groups of children methods differed significantly for stage I, with the exception of plethysmography. High R2 values were observed for girls in all Tanner stages. Each method explained between 34-92% of the variance in body fat percentage for girls in stages I and II and between 63-93% for stages III and V. In obese boys, R2 values were high for stages III and V. In girls and boys in Tanner stage III and V, the smallest differences were observed for isotopic dilution, and DXA (dual-energy X-ray absorptiometry) scan for stages I and II. CONCLUSIONS For obese boys and girls, the two compartment model with isotopic dilution and DXA had the best precision and smallest differences in determining body fat percentage compared to the benchmark.