Trends in the distribution of body mass index among Chinese adults, aged 20-45 years (1989-2000)

Objective: To describe body mass index (BMI, in kg/m(2)) distribution patterns and trends among Chinese adults, aged 20-45 years (1989-2000). Design: A descriptive, population-based study of BMI change. Setting: Chinese provinces (eight in 1989 and 1997; nine in 2000), representative of the household-based surveys (the China Health and Nutrition Survey, 1989-2000) using multistage, random cluster sampling, supplemented with annual household consumption survey data of the State Statistical Bureau (SSB). Subjects: A total of 4527, 4507 and 4046 adults, aged 20-45 years, in 1989, 1997 and 2000, respectively. Measurements: BMI ( underweight: BMI < 18.5 kg/m(2) and overweight: BM >= 25 kg/m(2)). Percentile curves for BMI in 1989 and 2000 were constructed by gender and age using the LMS ( lambda, mu, sigma) method. Results: Compared with 1989, the 2000 BMI distribution curves flattened at higher levels of BMI (men and women). There was a 13.7% increase in the proportion of men and a 7.9% increase of women who were overweight or obese with a resulting greater change in the annualized prevalence rate for men. This increase in the prevalence of overweight and obesity was far greater than the decrease (2.1% for men; 2.2% for women) in that of underweight. Age-gender-specific percentile curves showed BMI increases mainly among women, aged 35-45 years, and among men at all age groups. Conclusions: Chinese BMI dynamics show much greater rates of change among men, aged 20-45 years, than among women, with the increase among women concentrated between ages 35 and 45 years. These changes portend large shifts in other diet-related non-communicable diseases in China over the following decades. Controlling the increasing trends of BMI, especially in men, is an important public health problem facing China.