Abstract: This paper reviews the economic literature related to obesity and consumer decisions, pursuing the overall question, whether the current obesity epidemic and its social bias can be viewed as a result of rational consumption behaviour. We address a number of potential explanations based on consumers' utility maximisation behaviour, which all may contribute to explain the ongoing rise in obesity prevalence in many western countries. In addition to standard neoclassical explanations of obesity, we discuss moral hazard aspects, the role of network externalities, self-control problems and habitual behaviour. We include all of these aspects of the individual weight decision in a unified theoretical framework and present existing empirical evidence for each effect. Based on our analysis, we discuss the different economic explanations and give suggestions for future research.