Comparison of body mass index with body fat percentage in evaluation of overweight and obesity among rural adult women

Objective To evaluate the accuracy of body mass index(BMI) applied in China with body fat percentage(BF%) suggested by World Health Organization(WHO) in determining overweight and obesity among rural adult women in Hebei province.Methods From May through July 2013, a total of 648 women aged 18-59 years(mean age:36.7±11.4 years) were included in a cross-sectional survey in Yutian county of Hebei province.BF% was measured using bioelectrical impedance analysis(BIA) and anthropometric indices were measured using standard methods.The BMI criteria adopted by Chinese Adults Overweight and Obesity Prevention and Control Guidelines and WHO BF% were used to define overweight and obesity.Results The mean BMI of study participants was 24.74±3.97 kg/m² and the mean BF% was 28.54±7.04%.According to the criteria of WHO(BF%>35%) and of BMI≥28.0 kg/m², the prevalence of obesity was 18.98 and 20.06%, without significant difference(P>0.05).Compared with the overweight criterion of BF%(>30%), the BMI criterion for overweigh of ≥24 kg/m² showed a good sensitivity(87.38%) and specificity(79.06%), and the diagnostic consistence(Kappa value) was 0.66.Compared with the obesity criterion of BF%(>35%), the BMI criterion for obesity of ≥28 kg/m² had a moderate sensitivity(71.54%) but an excellent specificity(92.00%), and the Kappa value was 0.62.Regression analyses showed that BMI had a good conic correlation with BF%(R²=0.614, P<0.001).Conclusion Compared with the WHO BF% overweight(>30%) and obesity(>35%) criteria, both the overweight(BMI≥24 kg/m²) and obesity(BMI≥28 kg/m²) criteria of BMI present a good accuracy when applied among rural adult women in China.