Secular trends in body mass index and the prevalence of overweight and obesity among children and adolescents in Shandong, China, from 1985 to 2010

BACKGROUND: There is strong evidence of a positive secular trend in body mass index (BMI) and the prevalence of obesity has increased substantially over the last several decades. However, no studies on this trend have been reported in Shandong Province, China. The present study assessed the decennial change in BMI in Shandong Province during the past 25 years and the prevalence of overweight and obesity among children and adolescents. METHODS: The BMI of children and adolescents aged 7-18 was calculated using data from five national surveys on students' constitution and health carried out by the government in 1985, 1995, 2000, 2005 and 2010 in Shandong Province, China. The distribution of BMI was reported, and the prevalence of overweight and obesity was obtained according to the screening criteria of overweight and obesity for Chinese students using BMI [Working Group on Obesity in China (WGOC) standard]. Overweight and obesity prevalence were also computed using the International Obesity Task Force (IOTF) cutoffs. RESULTS: In the past 25 years, the P(50) (50th percentile) of BMI increased. The average increments of BMI were 2.18 kg/m(2) for boys and 1.21 kg/m(2) for girls, respectively. The prevalence of overweight and obesity increased rapidly: using WGOC standard, the prevalence of overweight increased from 1.91% for boys and 2.02% for girls in 1985 to 17.34% for boys and 11.97% for girls in 2010, and the prevalence of obesity increased from 0.27% for boys and 0.23% for girls in 1985 to 15.83% for boys and 7.12% for girls in 2010; using IOTF standard, the prevalence of overweight increased from 1.54% for boys and 1.27% for girls in 1985 to 19.06% for boys and 13.42% for girls in 2010, and the prevalence of obesity increased from 0.04% for boys and 0.03% for girls in 1985 to 9.33% for boys and 2.42% for girls in 2010, respectively. CONCLUSIONS: The average value of BMI has increased over time; overweight and obesity among children and adolescents have become a serious public health problem. Comprehensive evidence-based strategies of intervention should be introduced, including periodic monitoring.