Objective: Determine the association between waist circumference (WC) and percentage body fat (%BF) and to develop cut-off values and evaluate the accuracy of WC in the definition of obesity in rural Thai population.

Material and Method: A cross-sectional, epidemiologic study in 181 men and 255 women aged 50 ± 16 yr (mean ± SD; range: 20-84 yr) sampled by stratified clustering sampling method, was designed. Percentage body fat was measured by dual energy X-ray absorptiometry (GE Lunar Corp, Madison, WI). The “golden standard” for defining obesity was%BF ≥ 25 in men and%BF ≥ 35 in women. Waist circumference in centimeter was measured.

Results: In this study, the %BF-based prevalence of obesity in men and women was 8.3% and 44%, respectively. However, using the WC cut-off (WHO) of 102 cm in men and 88 cm in women, only 1.7% of men and 24% of women were classified as obese. WC was a significant predictor of %BF, such that in men, a WC of 93 cm would predict a %BF of 25%, and in women a WC of 84 cm would correspond to a %BF of 35%. The area under the receiver operating characteristic curve was 0.87 and 0.88 in men and women, respectively. In conclusion, waist circumference is a reasonably useful indicator of obesity.

Conclusion: The cut-off values of WC for diagnosing obesity should be lower in Thailand than in Western countries.

Keywords: Obesity, Waist circumference, Percentage body fat, Rural, Thailand