Longitudinal Effects of Body Mass Index on Chronic Diseases and Functional Decline among Chinese Older Adults

Background. Excess body weight contributes to increased morbidity and functional declines. Nutrition transition theory attributes this to large shifts in dietary habits and physical activity patterns. This study adds to limited literature examining how increased body mass index (BMI) affects chronic diseases and functional decline in older populations internationally.

Methods. Panel data from the China Health and Nutrition Survey (CHNS) was examined to assess how social and economic transformation in China affected the health and nutritional status of Chinese residents. All available data from 1997, 2004, 2004, and 2006 were analyzed from adults aged 60 years or older (N=3,829). Outcome variables were chronic diseases (i.e., diabetes, hypertension) and functional decline (i.e., limitation in activities of daily living (ADL) or instrumental activities of daily living (IADL)). Covariates included BMI, general health, and behavioral and social risk factors. A population-averaged model was used to identify risk factors of health outcomes and determine the effects of increased BMI on health outcomes.

Results. Demographic characteristics indicate that 27% of respondents were overweight or obese. Approximately 30% reported having diabetes and/or hypertension, while more than 42% reported ADL or IADL limitations. The final model showed that an increased BMI raised the odds of having diabetes and/or hypertension (OR=2.31) but decreased the odds of having functional declines (OR=0.80).

Conclusion. Given the sheer size of China's aging population and its increasing rates of obesity, public health researchers and policy makers need to pay more attention to the complexities involved in understanding obesity in a global health context.