Measurement of body fat using leg to leg bioimpedance

Aims-(1) To validate a leg to leg bioimpedance analysis (BIA) device in the measurement of body composition in children by assessment of its agreement with dual energy x ray absorptiometry (DXA) and its repeatability. (2) To establish a reference range of percentage body fat in Hong Kong Chinese chi ldren. Methods-Sequential BIA and DXA methods were used to determine body composit ion in 49 children aged 7-18 years; agreement between the two methods was c alculated. Repeatability for the BIA method was established from duplicate measurements. Body composition was then determined by BIA in 1139 girls and 1243 boys aged 7-16 years, who were randomly sampled in eight local primar y and secondary schools to establish reference ranges. Results-The 95% limits of agreement between BIA and DXA methods were consid ered acceptable (-3.3 kg to -0.5 kg fat mass and -3.9 to 0.6% body fat). Th e percentage body fat increased with increasing age. Compared to the 1993 H ong Kong growth survey, these children had higher body mass index. Mean (SD ) percentage body fat at 7 years of age was 17.2% (4.4%) and 14.0% (3.4%) r espectively for boys and girls, which increased to 19.3% (4.8%) and 27.8% ( 6.3%) at age 16. Conclusion-Leg to leg BIA is a valid alternative method to DXA for the meas urement of body fat. Provisional reference ranges for percentage body fat f or Hong Kong Chinese children aged 7-16 years are provided.