To analyze the prevalence and epidemic characteristics of obesity in China and provide the evidence for the early interventions to decrease the complications of obesity.

This population-based cohort study was based on China National Diabetes and Metabolic Disorders Survey. Data were collected during 2007-2008. A multi-stage stratified sampling method was used to select a nationally representative sample of Chinese adults aged no less than 20 years. A structured questionnaire was used to collect the information of physical examination. The cut-off values of BMI to define overweight and obesity were no less than 24 kg/m² and 28 kg/m², respectively. Abdominal obesity was diagnosed if the waist circumference (WC) was no less than 90 cm in men or no less than 85 cm in women. Body fat (BF) greater than or equal to 20% in man or 30% in women was considered to be obesity. The t test was applied in data analysis.

A total of 14 204 women and 9 718 men aged 20-88 years were included in this study. The average age was (45±14) years. Using BMI as a diagnostic standard, the prevalence of overweight and obesity were 46.51%(6 591/14 171) in women and 56.49% (5 473/9 688) in men. The prevalence of obesity were 13.37% (1 895/14 171) in women and 17.10% (1 657/9 688) in men. The prevalence of abdominal obesity were 37.73% (3 658/9 695) for men and 29.94% (4 141/14 165) for women when using WC as standard. When BF was used to define obesity, the prevalence were 77.79% (7 560/9 718) and 59.16% (8 403/14 204) in men and women, respectively. When using BF no less than 20% in men or 30% in women to define obesity, the corresponding cut off values of BMI were 23.0 kg/m² and 22.9 kg/m2, respectively.

Men have higher prevalence of overweight and obesity than women. Using BMI alone to evaluate obesity may not be suitable since this will underestimate the prevalence of obesity.

Obesity; Body mass index; Waist circumference; Body fat