RESUMEN
<p><b>OBJECTIVE</b>To understand the current status on prevalence of overweight and obesity in Chinese middle-aged population, and to quantify the magnitude of the trends of development in the past two decades.</p><p><b>METHODS</b>Body mass index (BMI) was measured on 15 389 middle-aged men and women from 15 natural populations all over China with different geographical, economical (urban/rural) and occupational status. Overweight was defined as BMI >/= 25 while obesity as BMI >/= 30.</p><p><b>RESULTS</b>1) The rates of prevalence on overweight and obesity varied dramatically between populations. 2) In general, the prevalence rates were higher in the northern areas, in urban areas, and in women. 3) The current problem of obesity was related to 'pre-obese' stage, with less than 10% in most populations. 4) The prevalence of overweight and obesity started to show significantly increase from early 80's to early 90's but more prominant in the late 90's.</p><p><b>CONCLUSION</b>Prevention and intervention of overweight and obesity are in urgent need in the Chinese populations, especially in those economically fast developing areas.</p>