Department of Economics

The modern prevalence and negative consequences of obesity suggest that many people have a tendency to eat more than is optimal. This paper examines the biological underpinnings of mammalian feeding behavior in an attempt to reconcile the “self-control problem” with the normative tradition of neoclassical economics. Medical, genetic, and molecular evidence suggest that overeating is a manifestation of the fundamental mismatch between ancient environments—in which preferences for eating evolved—and modern environments. The phenomenon can be described with a simple optimal foraging model in which both the utility function and the Bayesian prior are generated endogenously in the distant past. The implied disparity between subjective probabilities and actual probabilities has potentially broad implications for welfare economics.