Objective For prevention of obesity in Chinese population, it is necessary to definethe optimal range of healthy weight and the appropriate cut-off points of BMI and waistcircumference for Chinese adults. The Working Group on Obesity in China under the supportof International Life Sciences Institute Focal Point in China organized a meta-analysis on therelation between BMI, waist circumference and risk factors of related chronic diseases (e. g.,high diabetes, diabetes mellitus, and lipoprotein disorders). Methods 13 population studiesin all met the criteria for enrollment, with data of 239 972 adults (20-70 year) surveyed inthe 1990s. Data on waist circumference was available for 111411 persons and data on serumlipids and glucose were available for more than 80 000. The study populations located in21provinces, municipalities and autonomous regions in mainland China as well as inTaiwan. Each enrolled study provided data according to a common protocol and uniformformat. The Center for data management in Department of Epidemiology, Fu Wai Hospitalwas responsible for statistical analysis. Results and conclusion The prevalence ofhypertension, diabetes, dyslipidemia and clustering of risk factors all increased withincreasing levels of BMI or waist circumference. BMI at 24 with best sensitivity andspecificity for identification of the risk factors, was recommended as the cut-off point foroverweight, BMI at 28 which may identify the risk factors with specificity around 90 % wasrecommended as the cut-off point for obesity. Waist circumference beyond 85 cm for menand beyond 80 cm for women were recommended as the cut-off points for central obesity.Analysis of population attributable risk percent illustrated that reducing BMI to normalrange (<24) could prevent 45%-50% clustering of risk factors. Treatment of obese persons(BMI≥28)with drugs could prevent 15%-17% clustering of risk factors. The waistcircumference controlled under 85 cm for men and under 80 cm for women, could prevent47%-58% clustering of risk factors. According to these, a classification of overweight andobesity for Chinese adults is recommended. Objective For prevention of obesity in Chinese population, it is necessary to define the optimal range of healthy weight and the appropriate cut-off points of BMI and waist circumference for Chinese adults. The Working Group on Obesity in China under the support of International Life Sciences Institute Focal Point in China organized a meta-analysis on therelation between BMI, waist circumference and risk factors of related chronic diseases (eg, high diabetes, diabetes mellitus, and lipoprotein disorders). Methods 13 population studies all all the criteria for enrollment, with data of 239 972 adults (20-70 year) surveyed inthe 1990s. Data on waist circumference was available for 111411 persons and data on serum lipids and glucose were available for more than 80 000. The study populations located in 21provinces, municipalities and autonomous regions in mainland China as well as inTaiwan. Each enrolled study provided data according to a common protocol and uniformformat. The Center f or data management in Department of Epidemiology, Fu Wai Hospitalwas responsible for statistical analysis. Results and Conclusion The prevalence ofhypertension, diabetes, dyslipidemia and clustering of risk factors all increased withincreasing levels of BMI or waist circumference. BMI at 24 with best sensitivity andspecificity for identification of the risk factors, was recommended as the cut-off point for overweight, BMI at 28 which may identify the risk factors with specificity around 90% wasrecommended as the cut-off point for obesity. Waist circumference beyond 85 cm for menand beyond 80 cm for women were recommended as the cut-off points for central obesity. Analysis of population attributable risk percent illustrated that reducing BMI to normalrange (<24) could prevent 45% -50% clustering of risk factors. Treatment of obese persons (BMI> 28) with drugs could prevent 15% -17% clustering of risk factors. The waistcircumference controlled under 85 cm for men and under 80 cm for women ,could prevent 47% -58% clustering of risk factors. According to these, a classification of overweight andobesity for Chinese adults is recommended.