Validity of deuterium oxide dilution for the measurement of body fat among Singaporeans.

Body fat percent (BF%) was measured in 108 adult Chinese, 76 Malays, and 107 Indians in Singapore by densitometry, deuterium oxide dilution (hydrometry), dual energy x-ray absorptiometry (DXA) and a chemical four-compartment model (BF%4c). The hydration of the fat-free mass (FFM) was calculated. Subjects ranged in age from 18 to 69 years and their body mass index ranged from 16 to 40 kg/m2. BF%4c for the various subgroups were: Chinese females (33.5 +/- 7.5%), Chinese males (24.4 +/- 6.1%), Malay females (37.8 +/- 6.3%), Malay males (26.0 +/- 7.6%), Indian females (38.2 +/- 7.0%) and Indian males (28.1 +/- 5.5%). Biases were found between BF%4c and BF% measured by 2-compartment models (hydrometry, densitometry, DXA), with systematic underestimation by DXA and densitometry. On a group level hydrometry had the lowest bias while DXA gave the highest bias. When validated against BF%4c, 2-compartment models were found to be unsuitable for accurate measures of body fat due to high biases at the individual level and the violation of assumptions of constant hydration of FFM and density FFM among the ethnic groups. On a group level the best 2-compartment model for measuring body fat was found to be hydrometry.