Anthropometric and bioimpedance equations for fat and fat-free mass in Chilean children 7-9 years of age

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.

Automated summary

This study validated new FM% and FFM equations for Chilean children, providing a simple and valid tool for assessing body composition. The research demonstrated that using equations specific for children improved the accuracy of body composition assessment, offering a basis for cohort studies or evaluating the impact of nutritional programs or public policies.