Bioelectrical impedance as a measure of change in body composition in young children

Background and objectivesThe ability of bioelectrical impedance (BIA) to measure change in body composition in children has rarely been examined. MethodsBody composition was estimated by BIA (Tanita BC-418) and dual-energy x-ray absorptiometry (DXA) in 187 children aged 4-8 years at baseline and at 12 months. Change in body composition was compared between the two methods using mixed models. ResultsEstimates of change in fat mass did not differ between BIA and DXA for overweight girls (mean difference between methods, 95% confidence interval: 0.04kg, -0.19 to 0.28) or boys (0.07kg, -0.14 to 0.27). BIA was also able to accurately detect change in fat-free mass, with no significant differences between methods (-0.14kg, -0.10 to 0.38 in girls and -0.07kg, -0.35 to -0.20 in boys). Change in percentage fat produced similar estimates in both genders (0.18%, -0.82 to 0.46 in girls and 0.38%, -0.37 to 1.13 in boys). BIA/DXA comparisons in normal weight children were also not significantly different, with the exception of percentage fat in girls, where BIA slightly underestimated change compared with DXA (0.7%, 0.02-0.37). ConclusionBIA performed well as a measure of change in body composition, providing confidence for its use as an outcome measure in children.