Modeling the Effect of Physical Activity on Obesity in China: Evidence from the Longitudinal China Health and Nutrition Study 1989-2011.

Although physical activity has been widely recognized as an important influential factor in determining the risk of obesity, the results in the existing literature empirically examining such issue are mixed. Especially for China, relevant studies are rarely found. One aim of this study is to test the direction of effects between obesity and physical activity. It uses longitudinal data to investigate the relationship and causality between physical activity and obesity for both children and adults in China. The longitudinal data and dynamic panel model used here can yield more solid results than the other studies employing cross-sectional data, particularly considering strict endogeneity and self-selection. It is discovered that obesity does not affect children's physical activity but that obese children are more sedentary. For adults in China, physical activity can significantly reduce the weight, but not in the opposite direction.