Understanding overeating and obesity.

The combination of economic and biological factors is likely to result in overeating in the current environment of cheap and readily available food. This propensity is shown using a "dual decision" approach where choices reflect the interaction of a "deliberative" system, operating as in standard economic models, and an "affective" system that responds rapidly to stimuli without considering long-term consequences. This framework is characterized by excess food consumption and body weight, in that individuals prefer both ex-ante and ex-post to eat and weigh less than they actually do, with weight loss attempts being common but often unsuccessful or only partially successful. As in the standard model, weight is related to prices. However, another potentially important reason for rising obesity is that food producers have incentives to engineer products to stimulate the affective system so as to encourage overeating. Data from several sources are used to investigate predictions of the dual decision model, with the evidence providing broad support for at least some irrationality in food consumption. Most importantly, there is little indication that the large secular increases in body mass index have been accompanied by corresponding growth in utility-maximizing weight. One result is that efforts to reduce weight have become more common as obesity has increased.