A person’s body weight increases when he consumes more calories than he burns through both basic metabolism and exertion. If a person gains weight, there has been a shift in the calories he consumes or burns. Perhaps he treated himself to some birthday cake or cut back on going to the gym. The question is, do the benefits of the added weight exceed the costs? Does the pleasure from the birthday cake outweigh the slight increase in health costs from the weight gain? If it does, the person has increased his happiness. He has moved closer to his optimal weight.
In today’s world, optimal weight is likely higher than it was in generations past. Medical advances have lowered the costs of added weight, while advances in agriculture and culinary arts have lowered food costs and increased pleasure. Likewise, technological change has lessened the need for unpleasant but calorie‐burning toil. Researchers have scrutinized many factors that increase the benefits or decrease the costs of weight. These include increased consumption of sugar‐sweetened beverages, eating more food from restaurants, reduced cigarette smoking, urban sprawl, increased driving, technological change and agriculture policies that result in lower food prices. In some of those cases, there are arguments for policy change — increased obesity may be a good reason to cut farm subsidies, for example. But there is no clear justification for a government‐led “war on obesity” intent on forcing people to conform to some ideal of how we should look and live.
Nonetheless, government is intent on imposing that ideal. The federal Healthy People 2010 program has set goals of limiting obesity to just 15 percent of adults and 5 percent of children. It’s unclear why those percentages were chosen or even why a body mass index of 30 has been designated the “obesity” threshold. These numbers may have been chosen simply for convenience — they’re all nicely divisible by 5, after all. But they were not the product of a careful, publicly available analysis of optimal weight.
Anti‐obesity activists often justify government intervention by claiming that the non‐obese pay more for health insurance in order to subsidize higher medical expenses for the obese. However, economists have been hard‐pressed to find those subsidies. Special taxes have been levied on “junk food” under the rationale that public money goes to treating obesity, but plenty of non‐obese people eat lots of junk food, and there are plenty of other causes for obesity besides soda and potato chips. These taxes seem intended to garner populist acclaim instead of resulting from serious public policy. Besides, if cigarette taxes are any indication, junk‐food taxes ultimately will be diverted away from health care and weight‐loss programs and thrown into the general pot of government spending.
None of this is to say that we hope Americans keep gaining weight. We want Americans to become more fit — but that is our personal preference. We realize that government should not be used to impose personal preferences on the public. We wish anti‐obesity activists realized that, too.