[Study on the formulas predicted for body fat of children and adolescents by using bioelectrical impedence analysis].

OBJECTIVE

To modified the prediction formulas for bioelectrical impadance analysis on the fat free mass at different body mass index (BMI) levels of Chinese children and adolescents.

METHODS

Data of body composition of 468 boys and 457 girls aged 7-18 years living in Beijing measured by under water weighing were used to develop the equations of FFM for bio-electrical impedance.

RESULTS

The prediction formulas were:normal weight group: FFM(kg) = 0.406 weight + 2.918 sex + 0.315 H2/z + 0.843. over weight group: FFM(kg) = 0.358 weight + 1.571 sex + 0.358 H2/z + 0.603. Total population: FFM(kg) = 0.290 weight + 2.222 sex + 0.427 H2/z + 1.547. The regression equations with the corresponding explained variance (r2) and the standard error of estimate (SEE) in normal, over weight and total population group are 0.940, 2.36, 0.955, 2.46 and 0.942, 2.53 respectively. The significant of the regression were tested by the ANOVA (P < 0.001).

CONCLUSION

The explained variance and the prediction error of the formuals were improved compared to the literature by using,the classification screening standard of age- and sex-specific BMIs for overweight and obesity of Chinese school children to divide groups.