Waistlines Are Now Victims of Economic Progress

Americans' waistlines have become the victims of economic progress.

The New York Times, "Economic Scene" , March 22, 2001

Ever alert for trends that threaten Americans' health, the Centers for Disease Control and Prevention recently reported some bad news. Only about a quarter of the population is getting enough exercise, and that percentage barely budged from 1990 to 1998. The media may be full of beautiful, fit bodies, but neither those images nor the pleading of health experts is having much effect. Most Americans seem content to stay on the couch. The result is ever greater obesity.

That doesn't surprise Tomas J. Philipson, an economist at the Irving B. Harris Graduate School of Public Policy Studies at the University of Chicago. Professor Philipson, who applies economic reasoning to public health questions, recently examined the reasons behind increasing obesity. "People understand better now how to control their weight than historically," he notes. "The information has grown, but we're yet getting fatter over time." Something other than ignorance must be driving the trend.

In a National Bureau of Economic Research working paper written with Richard A. Posner, a federal appeals court judge affiliated with the University of Chicago Law School, Professor Philipson proposes a simple theory. People haven't changed -- they've always liked to eat high-calorie food and generally disliked strenuous exertion -- but incentives have. (The paper, "The Long-Run Growth in Obesity as a Function of Technological Change," can be found here.)

For starters, the cost of consuming calories has plummeted, thanks to productivity gains in agriculture and distribution. Food is cheaper and more abundant, encouraging people to consume more of it. But that's an old trend, and it doesn't fully account for recent weight gains.

More important in recent years is that the cost of burning those calories has surged as work has become more sedentary. "To put it simply, it used to be that you got paid to exercise," Professor Philipson says. "If you wanted an income, you engaged in manual labor. Today you pay to exercise, not so much in money, but in forgone leisure time. So if you want to spend time with your kids, you have a choice between that and going to the gym or running." To burn a lot of calories, Americans have to give up doing other valuable things. Exercise is no longer something free that comes along with making a living.

That's good news for the people in the health club business. The International Health, Racquet and Sportsclub Association reports record numbers of members and rising participation. But the nation's 31 million health club members account for just over 10 percent of the population. And only 40 percent of those go to the gym at least twice a week, a rising percentage but still a small one.

"One interpretation of why you've gotten such an explosion in leisure exercise is because work exercise has gone down," Professor Philipson says. "We didn't used to have people going out jogging or going to the gym after work because they got it at work." While leisure exercise was fairly stable in the 1990's, over the long run it has been going up -- just not fast enough to make up for those lost paid workouts.

This theory helps to explain an empirical puzzle. In the United States, poorer people tend to be fatter than rich ones. (The very poorest Americans are still thin, but weight rises rapidly from there, with the heaviest people in the low-to-middle incomes -- an inverted U-shaped curve.) Around the world, however, people in poor countries are skinnier than people in wealthy countries.

"One interpretation of that is that the same technological differences that generate higher per capita income in the rich countries also make them more sedentary," Professor Philipson says. As national income rises, so does the average weight, "because those guys are having desk jobs instead of cutting wheat."

In developed countries, thinness is a costly good that people demand more of as they get wealthier. Not surprisingly, health club members have relatively high incomes, with nearly a fifth reporting household incomes of more than $75,000. The sharp increase in paid labor among women the last three decades may account for the rapid rise in their weights. Housework, while only moderately strenuous, is more physically demanding than sitting at a desk.

And if women still have the after-hours housework responsibilities, they have less leisure time than men for more intensive exercise, like health club workouts. Burning calories is thus particularly costly for women.

Professor Philipson is testing the work-exercise theory in empirical work with Darius Lakdawalla of the RAND Corporation, using data on how strenuous various occupations are. (These data are usually used in computing worker's compensation insurance rates.) The preliminary results suggest "huge effects of this work-related exercise" on obesity, Professor Philipson says. People in more strenuous jobs are significantly thinner than people of similar backgrounds and incomes who get less exercise at work.

In this view, Americans aren't getting fatter because they don't know what's good for them or because they've suddenly developed a taste for fatty foods. They haven't exchanged self-control for gluttony. Rather, the same economic and technological progress that has produced higher living standards has made work more sedentary. (For children, the issue is entertainment rather than work -- the difference between playing tag and playing video games.) Growing obesity is an unintended consequence of a more productive economy.

This analysis has implications for other health and technology issues. The increasingly popular "precautionary principle" warns against adopting technologies, like genetically enhanced foods, that might have negative side effects. To see the principle's problems, we need only consider the causes of obesity, a far better established health risk than anything the antigenetics campaigners have dreamed up. Would we really be better off picking cotton and cutting wheat by hand? We'd be thinner, true, but with shorter, less interesting lives -- and a whole new collection of physical ailments. Americans may not want to be overweight, but they prefer it to the alternatives.