OBJECTIVEIn order to develop strategies on prevention and cure for obesity, a study regarding dynamic analyses on the prevalence of obesity and overweight of Chinese children and adolescents was carried out.

METHODSData of more than 980 thousands students of Han nationality, aged 7 through 18 years old were collected from National Surveys on Chinese Students' Constitution and Health which were carried out in 1985, 1991, 1995 and 2000. Samples were divided into four groups as "metropolis", "medium and small sized cities", "prosperous village" and "below-averaged village". Study targets were screened using the new criterion-the "Reference Norm for Screening Overweight and Obesity in Chinese Children and Adolescents" which was set up by the Working Group on Obesity in China. The prevalence of overweight and obesity in various groups in different years were compared and analyzed.

RESULTSThe prevalence rates of obesity in 1985 including from the metropolis area, were only 0.2% and 0.1% for boys and girls, and the prevalence of overweight was between 1% and 2% indicating that was no trend of obesity epidemic then. However, a rapid increase of overweight prevalence has been noticed since the early 1990s, and the increments were more seen in the urban than in the rural areas and more in boys than in girls. In the most developed cities including Beijing, the prevalence rates of obesity appeared to be 4.7%, 3.8% and 3.2%, among three groups with higher risk: the 7 - 9, 10 - 12 year-old boys and 7 - 9 year-old girls, respectively. Both high prevalence rates of malnutrition and overweight were also found in that period. Around 1995, a large scale of increments of overweight were found both in the urban and rural groups. In the most developed metropolis, the prevalence of overweight was two to three folds more than that of 10 years ago. The prevalence of obesity were 6% - 8% for boys and 4% - 6% for girls, respectively. Since 2000, most of the Chinese metropolis have started the so called 'overall increment period' of obesity. The prevalence rates of obesity plus overweight had reached 25.4%, 25.5%, 17.0% and 14.3% for boys aged 7 - 9 years and 10 - 12 years, and girls aged 7 - 9 years and 10 - 12 years, respectively. Among them, the prevalence rates of obesity were 12.9% and 9.1% for boys aged 7 - 9 and 10 - 12 years, which had already reached the average level seen in the medium-developed countries in the world. Although the increments of overweight were high, the prevalence of obesity was still low in most of the other groups: 4.8% for boys and 2.6% for girls in the "medium sized" group, 1.5% for boys and 1.7% for girls in the "prosperous village" group, and 0.9% for boys and 1.2% for girls in the "below-averaged village" group, respectively.

CONCLUSIONSThe prevalence of obesity in Chinese children and adolescents was considered to be still relatively low. However, the rapid increasing of both obesity and overweight, in both urban and rural areas would arouse special attention. Comprehensive strategies of intervention should include periodical monitoring, education on pattern of nutrition, oxygen-consuming physical exercises and healthy dietary behavior. Two areas on obesity prevention to protect the child from becoming overweight in early ages, and to control the tendency of obesity from overweight, should be emphasized in order to improve the health status and life quality of the Chinese children and adolescents.