Body mass index and waist circumference are good indicators for classifying children's nutritional status.

This study aimed to investigate the relationship between anthropometric indicators - body mass index (BMI), waist circumference (WC), and waist-to-height ratio (WHtR) - and the sum of skinfold thicknesses in 7-10-year-old children attending a public school in São Paulo (SP). Height, weight, WC and triceps, biceps, subscapular and suprailiac skinfolds were measured, and the sum of skinfold thicknesses, BMI and WHtR were calculated. A Bland-Altman analysis was used in order to compare methods, with values transformed into z-scores. The analysis of limits of agreement and confidence intervals showed evidence of good agreement, above all between BMI and WC, and the sum of skinfold thicknesses, complying with strict agreement limits and differences smaller than 1 standard deviation (SD). WHtR showed moderate limits of agreement, from -1.02 to + 0.64 SD (boys) and -0.74 to + 1.12 SD (girls); its performance was not better than that of WC alone, the lower and upper limits of agreement for which were -0.91 to + 0.58 SD (boys) and -0.56 to + 0.89 SD (girls). The results support the use of anthropometric indicators to classify nutritional status, above all BMI and WC, in that both are similar when classifying children according to body fatness, and confer the advantages of being easy to obtain and affordable.