Estimation of body fatness from body mass index and bioelectrical impedance: comparison of New Zealand European, Maori and Pacific Island children.

摘要

OBJECTIVE:: To compare percentage body fat (%BF) for a given body mass index (BMI) among New Zealand European, Maori and Pacific Island children. To develop prediction equations based on bioimpedance measurements for the estimation of fat-free mass (FFM) appropriate to children in these three ethnic groups. DESIGN:: Cross-sectional study. Purposive sampling of schoolchildren aimed at recruiting three children of each sex and ethnicity for each year of age. Double cross-validation of FFM prediction equations developed by multiple regression. SETTING:: Local schools in Auckland. SUBJECTS:: Healthy European, Maori and Pacific Island children (n=172, 83 M, 89 F, mean age 9.4+/-2.8(s.d.), range 5-14 y). MEASUREMENTS:: Height, weight, age, sex and ethnicity were recorded. FFM was derived from measurements of total body water by deuterium dilution and resistance and reactance were measured by bioimpedance analysis. RESULTS:: For fixed BMI, the Maori and Pacific Island girls averaged 3.7% lower %BF than European girls. For boys a similar relation was not found since BMI did not significantly influence %BF of European boys (P=0.18). Based on bioimpedance measurements a single prediction equation was developed for all children: FFM (kg)=0.622 height (cm)(2)/resistance+0.234 weight (kg)+1.166, R(2)=0.96, s.e.e.=2.44 kg. Ethnicity, age and sex were not significant predictors. CONCLUSIONS:: A robust equation for estimation of FFM in New Zealand European, Maori and Pacific Island children in the 5-14 y age range that is more suitable than BMI for the determination of body fatness in field studies has been developed. SPONSORSHIP:: Maurice and Phyllis Paykel Trust, Auckland University of Technology Contestable Grants Fund and the Ministry of Health.European Journal of Clinical Nutrition (2003) 57, 1394-1401. doi:10.1038/sj.ejcn.1601701