OBJECTIVE: Obesity, as measured by body mass index, is highly prevalent in Native American children, yet there are no valid equations to estimate total body fatness for this population. This study was designed to develop equations to estimate percentage body fat from anthropometry and bioelectrical impedance as a critical part of Pathways, a multisite study of primary prevention of obesity in Native American children. DESIGN: Percentage fat was estimated from deuterium oxide dilution in 98 Native American children (Pima/Maricopa. Tohono O'odham and White Mountain Apache tribes) between 8 and 11 y of age. The mean fat content (38.4% ± 8.1%) was calculated assuming the water content of the fat-free body was 76%. Initial independent variables were height, weight, waist circumference, six skinfolds and whole-body resistance and reactance from bioelectrical impedance (BIA). RESULTS: Using all-possible-subsets regressions with the Mallows C (p) criterion, and with age and sex included in each regression model, waist circumference, calf and biceps skinfolds contributed least to the multiple regression analysis. The combination of weight, two skinfolds (any two out of the four best: triceps, suprailiac, subscapular and abdomen) and bioelectrical impedance variables provided excellent predictability. Equations without BIA variables yielded r2 almost as high as those with BIA variables. The recommended equation predicts percentage fat with a root mean square error = 3.2% fat and an adjusted r2 = 0.840. CONCLUSION: The combination of anthropometry and BIA variables can be used to estimate total body fat in field studies of Native American children. The derived equation yields considerably higher percentage fat values than other skinfold equations in children.
Bibliographical noteFunding Information:
We acknowledge the skilled technical assistance of D Nelson, K Booth, J White, J Palo, and S Levin. We are grateful for the collaborative contributions of B Broussard and the expertise for deuterium oxide analysis provided by K Schultze. We are also grateful for the cooperation of the Gila River and Tohono O'odham communities and the White Mountain Apache Indian community in Arizona, especially the children whose participation made this study possible. This work was supported by the National Heart, Lung and Blood Institute, NIH.
- Bioelectrical impedance
- Body fat
- Deuterium oxide
- Native Americans