Background: Most previous studies on trends in the prevalence of obesity or abdominal obesity in Chinese adults were based on regional data and/or short time intervals, and recent trends are not available. We aimed to examine the secular trends in the prevalence of overweight, obesity, and abdominal obesity among Chinese adults at the national level from 1993 to 2015.

Methods: A total of 70,242 Chinese adults aged 18-80 years were from the cross-sectional surveys conducted from 1993 to 2015. According to the World Health Organization criteria, overweight was defined as body mass index (BMI) ≥23.0 kg/m² and <27.5 kg/m², and obesity was defined as BMI ≥27.5 kg/m². According to the International Diabetes Federation criteria, abdominal obesity was defined as waist circumference (WC) ≥90 cm for men and ≥80 cm for women. Mean values and prevalence of adiposity markers were standardized to the age distribution of the China population in 2010.

Results: Between 1993 and 2015, and based on age-standardized values, mean BMI increased from 21.9 kg/m² in 1993 to 23.9 kg/m² (+2.0 kg/m²) in 2015 (P for trend < 0.001), and mean WC increased from 76.0 cm to 83.4 cm (+7.4 cm) (P for trend <0.001). From 1993 to 2015, the prevalence increased from 26.6% to 41.3% (+14.7%) for overweight, from 4.2% to 15.7% (+11.5%) for obesity, and from 20.2% to 46.9% (+26.7%) for abdominal obesity (all P for trends < 0.001). In multivariate linear regression analysis, time (calendar years), older age and urban regions were strongly and independently associated with BMI.

Conclusions: The prevalence of overweight, obesity, and abdominal obesity increased markedly among Chinese adults during the past two decades. Weight control programs and public health measures to address the societal causes of obesity should be strengthened.