Alterations in growth and body composition during puberty. I. Comparing multicompartment body composition models

Abstract

A four-compartment (4C) model of body composition was used as a criterion to determine the accuracy of three-compartment (3C) and two-compartment (2C) models to estimate percent body fat (%BF) in prepubertal and pubertal boys (genital I & II, n = 17; genital III & IV, n = 7) and girls (breast I & II, n = 8; breast III & IV, n = 15). The 3C water-density (3C-H2O) and 3C mineral-density models, dual-energy X-ray absorptiometry, the Lohman age-adjusted equations, the Slaughter et al. skinfold equations, and the Houtkooper et al. and Boileau bioelectrical impedance equations were evaluated. Agreement with the 4C model increased with the number of compartments (i.e., body water, bone mineral) measured. Except for the 3C-H2O model, the limits of agreement were large and did not perform well for individuals. The mean %BF by dual-energy X-ray absorptiometry (23.6%) was greater than that of the criterion 4C method (21.7%). For the field methods, the Slaughter et al. skinfold equations performed better than did the Houtkooper et al. and Boileau bioimpedance equations. The hydration of the fat-free mass decreased (genital I & II = 75.7%, genital III & IV = 74.8%, breast I & II = 75.5%, breast III & IV = 74.4%) and the mineral content increased (genital I & II = 4.9%, genital III & IV = 5.0%, breast I & II = 5.1%, breast III & IV = 5.7%) with maturation. The density of the fat-free mass also increased (genital I & II = 1.084 g/ml, genital III & IV = 1.087 g/ml, breast I & II = 1.086 g/ml, breast III & IV = 1.091 g/ml) with maturation. All of the models reduced the %BF overprediction of the Siri 2C model, but only the 4C and 3C-H2O models should be used as criterion methods for body composition validation in children and adolescents.

Body composition techniques and the four-compartment model in children

“…Thus some of the upper limb fat mass may have been left out in the calculation of fat mass by the computer software. To our knowledge, this is the first study to crossvalidate the DXA against the 4C model in children using the Lunar DPX-L. Roemmich et al (20) found similar results using a Hologic DXA. That study found percent fat estimates by DXA to be systematically 3 1.0332 Ϯ 0.0204 Body density from HW, g/cm 3 1.0384 Ϯ 0.0187* TBW kg 25.9 Ϯ 6.9…”

“…1) To correct for isotope exchange with nonaqueous hydrogen atoms, we used a correction of 1.04, whereas others used a smaller correction (0.95-0.97), thus reducing our estimates of TBW by ϳ6% (1, 13, 14). 2) Children in our group were substantially heavier and more obese than those in the studies of Hewitt et al and Roemmich et al (13,20). This could potentially lead to more variation in the estimates of TBW.…”

Comparison of body fatness measurements by BMI and skinfolds vs dual energy X-ray absorptiometry and their relation to cardiovascular risk factors in adolescents

“…In a group of prepubertal children, the Slaughter formulas were moderately effective, explaining only 69% of the variance in the DXA fat mass, 28 and in a group of 47 10-13-y-old children the Slaughter formula was significantly better (r ¼ 0.79) than other skinfold equations in predicting %BF when compared to DXA. 29 In the present population of healthy adolescents, estimates of body fatness utilizing the Slaughter formulas were significantly correlated with DXA measurements. From the previous data and from the present study it can be concluded that measures of fatness derived from the Slaughter formulas provide adequate information for purposes of ranking individual degrees of adiposity within a population.…”

“…First, DXA estimates of body composition are known to be influenced by the higher degree of soft tissue hydration in younger children. 29,32 Second, there would likely be substantial differences in total body fat in an older cohort, since body size changes significantly with pubertal development. Similarly, the relations between measures of body fatness were not significantly different in short compared to tall children.…”

“…The characteristics and physical concepts of DXA have been previously described. 28,29 All metal objects (jewelry, snaps and belts) were removed before the scan. Measurements were taken with the subject supine on the scanning table, beginning at the top of the head and moving in a rectilinear pattern down the body to the feet.…”