The recent rise in obesity has generated enormous popular interest and policy concern in developing countries, where it is rapidly becoming a major health problem. But obesity (which we define broadly and loosely as weight significantly in excess of what the health-care industry deems normal) is not only a public health issue; it is also an economic problem in several respects. First, it is, in major part at least, a function of two choices that people make: the number of calories to consume and the number to expend; the more the former number exceeds the latter, the more weight a person will gain. Consuming calories comes with costs and benefits, and likewise expending calories through exertion. Second, obesity has changed over time and differs across populations; and, to the extent that it is a product of choice, explaining these changes and differences is a task for economics. The rate of the rise in obesity will also depend on biological factors that vary, within a range, across persons and time, but such factors alone, including genes, cannot explain the rise in obesity, because it has happened much too quickly to be explicable in evolutionary terms. Third, obesity may create social as well as private costs, and, if so, there is a question whether the government should intervene to try to reduce obesity. Fourth, the answer to that question depends, to the economist, on the cost of alternative methods of public intervention and the benefits, in reducing the social costs of obesity, that each method can be expected to produce. A growing scholarly literature in economics and other social sciences addresses the growth in obesity. We shall discuss the positive and normative analysis of obesity found in that literature, but our particular focus is a recent anthology of articles, primarily economic, on obesity.

Tomas J. Philipson is a visiting scholar at AEI. Richard Posner is a judge on the U.S. Court of Appeals for the Seventh Circuit.

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