This paper explores the effects of relative food prices on body weight and body fat over time in China. We study a cohort of 15,000 adults from over 200 communities in China, using the longitudinal China Health and Nutrition Survey (1991-2006). While we find that decreases in the price of energy-dense foods have consistently led to elevated body fat, this price effect does not always hold for body weight. These findings suggest that changes in food consumption patterns induced by varying food prices can increase percentage body fat to risky levels even without substantial weight gain. In addition, food prices and subsidies could be used to encourage healthier food consumption patterns and to curb obesity.