Body fat measurement among Singaporean Chinese, Malays and Indians: a comparative study using a four-compartment model and different two-compartment models

This cross-sectional study compared body fat percentage (BF%) obtained from a four-compartment (4C) model with BF% from hydrometry (using (H2O)-H-2), dual-energy X-ray absorptiometry (DXA) and densitometry among the three mai n ethnic groups (Chinese, Malays and Indians) in Singapore, and determined the suitability of two-compartment (2C) models as surrogate methods for ass essing BF% among different ethnic groups. A total of 291 subjects (108 Chin ese, seventy-six Malays, 107 Indians) were selected to ensure an adequate r epresentation of age range (18-75 years) and BMI range (16-40 kg/m(2)) of t he general adult population, with almost equal numbers from each gender gro up. Body weight was measured, together with body height, total body water b y (H2O)-H-2 dilution, densitometry with Bodpod(R) and bone mineral content with Hologic(R) QDR-4500. BF% measurements with a 4C model for the subgroup s were: Chinese females 33.5 (SD 7.5), Chinese males 24.4 (SD 6.1), Malay f emales 37.8 (SD 6.3), Malay males 26.0 (SD 7.6), Indian females 38.2 (SD 7. 0), Indian males 28.1 (SD 5.5). Differences between BF% measured by the 4C and 2C models (hydrometry, DXA and densitometry) were found, with underesti mation of BF% in all the ethnic-gender groups by DXA of 2.1-4.2 BF% and by densitometry of 0.5-3.2 BF%). On a group level, the differences in BF% betw een the 4C model and (H2O)-H-2 were the lowest (0.0-1.4 BF% in the differen t groups), while differences between the 4C model and DXA were the highest. Differences between the 4C model and (H2O)-H-2 and between the 4C model an d DXA were positively correlated with the 4C model, water fraction (f(water )) of fat-free mass (FFM) and the mineral fraction (f(mineral)) of FFM, and negatively correlated with density of the FFM (D-FFM), while the differenc e between 4C model and densitometry correlated with these variables negativ ely and positively respectively (i.e. the correlations were opposite). The largest contributors to the observed differences were f(water) and D-FFM. W hen validated against the reference 4C model, 2C models were found to be un suitable for accurate measurements of BF% at the individual level, owing to the high errors and violation of assumptions of constant hydration of FFM and D-FFM among the ethnic groups. On a group level, the best 2C model for measuring BF% among Singaporeans was found to be (H2O)-H-2.