Comparison of Body Mass Index with Body Fat Percentage in the Evaluation of Obesity in Chinese

Objective To evaluate the present Chinese body mass index（BMI） criteria with body fat percentage（BF%） in determining obesity in Chinese population.Methods A total of 4 907 subjects（age:20-90 yrs） were enrolled in the baseline survey of a longitudinal epidemiological study,and 2 638 of them were reevaluated in 5.5 years later.The Chinese BMI and WHO BF%were used to define obesity,respectively.Results The diagnostic agreement between the Chinese BMI and WHO BF%definitions for obesity was poor for both men（kappa:0.210,95%CI:0.179-0.241） and women（kappa:0.327, 95%CI:0.296-0.358）.However,BMI had a good correlation with BF%both in men（r:0.785,P<0,01） and women（r:0.864, P<0.01）.The age and sex-adjusted relative risks（RR） for incidence of type 2 diabetes（T2DM） were significantly higher in subjects with intermediate BF%（BF%:20.1%-25%for men,30.1%-35%for women）（RR:2.35,95%CI:1.23-4.48） and high BF%（BF%>25%for men and>35%for women）（RR:2.89,95%CI:1.43-5.81）,or in subjects with high BMI（BMI≥28 kg/m2）（RR:2.46,95%CI:1.31-4.63） when compared to those with low BF%（BF%≤20%for men and≤30%for women） or low BMI（BMI<24 kg/m2） respectively.No difference in risk could be found in those with intermediate BMI（BMI:24-27.9 kg/m2）（RR:1.44,95%CI:0.86-2.40）,as compared to those with low BMI（BMI<24 kg/m2）,whose BF%ranged widely from 7.8 to 50.3%.Conclusion BMI was correlated with BF%.Both BMI and BF%were associated with high risk for T2DM. However,BMI had its limitations in the interpretation of subjects with BMI between 24 and 27.9 kg/m2.