Abstract
We develop a mathematical model of obesity in which individuals value consumption but also have a concern for their body weight, a concern that may be inuenced by peers and that may be hampered by a lack of self-control. Our model is thus focused on the interplay between economic, social and psychological factors. It is general but yet tractable enough to permit analysis of a range of factors that have been put forward as relevant to obesity. The model sheds light on stylized facts about the obesity epidemic of the last thirty years and can be used to simulate policy effects and as a workhorse in theoretical and empirical research of obesity.