Abstract

Assessing children's growth adequately is important due to the necessary prevention of adequate body composition, especially at pre-pubertal age. Simpler measurements such as anthropometry or bioimpedance, using equations validated in Caucasian children, have been demonstrated to overestimate or underestimate fat mass percentage (FM%) or fat-free mass (FFM) in Chilean children. In a sample of 424 children (198 boys and 226 girls) of 7-9 years old, the three component (3C) model was assessed, where total body water was determined by H-2 dilution and body volume by air displacement plethysmography, in order to design and validate anthropometry and bioimpedance equations. The FM (%) equation specific for Chilean children was validated as (1 center dot 743 x BMI z-score) + (0 center dot 727 x triceps skinfold) + (0 center dot 385 x biceps skinfold) + 15 center dot 985, against the 3C model (R (2) 0 center dot 79). The new FFM equation (kg) generated was (log FFM = (0 center dot 018 x age) + (0 center dot 047 x sex) + (0 center dot 006 x weight) + (0 center dot 027 x resistance) + 2 center dot 071), with an R (2) 0 center dot 93 (female = 1 and male = 2). The Bland-Altman analysis shows a mean difference of 0 center dot 27 (sd 3 center dot 5) for the FM% in the whole group as well as 0 center dot 004 (sd 0 center dot 9) kg is the mean difference for the bioelectrical impedance analysis (BIA) FFM (kg) equation. The new equations for FM (%) and FFM (kg) in Chilean children will provide a simple and valid tool for the assessment of body composition in cohort studies or to assess the impact of nutritional programmes or public policies.