Estimating body fat in African American and white adolescent girls: a comparison of skinfold-thickness equations with a 4-compartment criterion model.

Background: Although skinfold-thickness equations are widely used to estimate body fat, their accuracy in a biracial population of female adolescents has not been established.
Objective: We undertook this study to determine the agreement between 8 widely used skinfold-thickness equations and a 4-compartment criterion model in predicting the percentage body fat of 72 white and 40 African American girls aged 13.0 +/- 1.9 y.
Design: The biceps, triceps, suprailiac, subscapular, thigh, calf, and abdominal skinfold thicknesses of the subjects were measured with skinfold calipers and the buttocks circumference with a metal tape. The percentage fat mass (%FM) predicted by using each skinfold-thickness equation was compared with the criterion value calculated by the 4-compartment model on the basis of measurements of body density, body water, and bone mineral content.
Results: When the racial groups were analyzed separately, the Bland-Altman analysis indicated that the quadratic equations agreed most closely with the 4-compartment model's measurement of %FM. Agreement of the other equations varied with body fatness.
Conclusions: The quadratic equation of Slaughter et al is recommended for population studies in female adolescents because of its accuracy and simplicity. However, an individual %FM can be over- or underestimated by approximately 10% when this skinfold-thickness equation is used.