Smoothed percentage body fat percentiles for U.S. children and adolescents, 1999-2004.

BACKGROUND The high prevalence of obesity (defined by body mass index) among children and adolescents in the United States and elsewhere has prompted increased attention to body fat in childhood and adolescence. OBJECTIVE This report provides smoothed estimates of major percentiles of percentage body fat for boys and girls aged 8-19 years in the United States. METHODS Percentage body fat was obtained from whole-body, dual-energy x-ray absorptiometry (DXA) scans conducted during the 1999-2004 National Health and Nutrition Examination Survey. A nonparametric double-kernel method was employed to smooth percentile curves for the DXA data. RESULTS The pattern of body fat development differs between boys and girls aged 8-19 years. In most age groups, girls have a higher percentage of body fat than boys. Among boys, there is a drop in body fat percentage in early adolescence that is especially pronounced at the higher percentiles. Among girls this pattern is not seen; percentage body fat increases slightly with age. CONCLUSIONS These results provide a smoothed reference distribution of percentage body fat for U.S. children and adolescents aged 8-19 years.