Assessment of adiposity by bio impedance analysis: developing a population specific equation for Sri Lankan adolescents

Abstract

Objective: Adiposity in adolescence is associated with chronic disease in adulthood, and assessment of body fat mass is vital for screening at risk populations. Adiposity is measured in many ways including bio impedence analysis. The objective of this study was to validate existing bio impedance analysis (BIA) equations on 15-19 year old adolescent girls and to derive a population specific equation for the prediction of percentage fat mass (%FM) for adolescent girls.Methods: Body composition of 15 -19 year old, adolescent girls was assessed by the deuterium dilution method and BIA. Validity of existing equations for the prediction of %FM of Sri Lankan adolescent girls were assessed prior to the derivation and validation of a new %FM equation. The new equation was derived using linear regression analysis against the reference method, deuterium dilution.Results: Existing BIA equations significantly (p< 0.001) overestimated %FM. The new equation derived for the prediction of %FM of Sri Lankan adolescent girls significantly correlated with the reference method. There was no significant difference in %FM obtained by the reference method (%FM: 24.67 ± 9.2) and the derived equation (%FM: 24.9 ± 6.3). Conclusions:The new equation; %FM = -74.065 + 0.671 (height 2 / resistance) + 0.049 (resistance) + 2.080 (BMI), is appropriate for the prediction of %FM in Sri Lankan post pubertal adolescent girls, and may be validated for use on other South Asian populations.