Human Ecology professor John Cawley uses economics to study the causes—and consequences—of America's obesity epidemic
Human Ecology professor John Cawley uses economics to study the causes—and consequences—of America's obesity epidemic
Cornell Alumni Magazine: Why would an economist study obesity?
John Cawley: A lot of people think that economics is about interest rates, trade deficits, and these abstract concepts that don't have much to do with everyday life. But economics is a social science—it's a study of why people make the decisions they do. And in particular, economists look at how people's behavior is affected by the trade-offs they face.
CAM: What does that have to do with being overweight?
JC: There's the saying, "A moment on the lips means a lifetime on the hips." It's the idea that when you're thinking about eating, you're considering the trade-offs. You have to weigh the benefits of instant gratification with the long-term consequences.
CAM: What sorts of things have you been looking at?
JC: I've been documenting direct medical costs of obesity; the transition from welfare to work among obese people; how obese children experience delayed skill attainment; the role of food advertising in decision-making about diet. When it comes to treatment, I've done studies of who takes anti-obesity drugs and what happens when the drugs are taken off the market. I've looked at bariatric surgery as well as the impact of physical education for high school students. I've evaluated various antiobesity programs in inner-city high schools and at worksites. I've looked at a lot of labor market outcomes—for example, documented that obese women earn significantly less than women who are healthy weight, but that wage penalty is pretty much limited to white females.
CAM: Why obese white women?
JC: Psychologists have demonstrated that there's a lot of bias and discrimination against obese individuals. We also find that obesity results in greater job absenteeism among women than men, so to some extent, this wage penalty could be the result of missing more work. Why it's white females in particular is harder to say, but sociologists and psychologists have found that optimal body size is larger in African American and Hispanic communities, so obese women in those groups may be less likely to suffer low self-esteem or depression.
CAM: Since the medical costs of obesity are so high, doesn't it make economic sense to invest in prevention?
JC: This is something employers really want to know, and it's tough to answer, because people don't work for the same firm their whole lives anymore. So you not only have to show that a worksite health-promotion program works, but that it pays for itself in a short enough period of time that the employer who pays for it will be the one who recoups the costs. The same is true for health insurers. Obesity is something that people struggle with their entire lives—so employers and insurers may conclude that they can't recoup the costs of weight loss programs.
CAM: Last year, you published a study on offering modest cash incentives for people to lose weight. Did it work?
JC: It wasn't very successful. A lot of people dropped out, and the ones who stayed didn't lose much weight. It's interesting, because this works well with other addictions. If you pay heroin or cocaine users $3 every time they have a negative test result, it dramatically increases the probability of adherence. This underscores how hard it is to lose weight and keep it off. The vast majority of weight loss attempts fail.
CAM: How did you get into studying the economics of obesity?
JC: When I was in grad school, I became interested in health disparities. I also got interested in addiction, and there are economic models of addiction that have been applied ad nauseam to alcohol, tobacco, drugs, and gambling. I wanted to think of a new application. I thought about anorexia—why do you become addicted to denial? But then I thought, If you look at the numbers, the percentage of Americans who are obese is enormously larger than the percentage who are underweight. From there I've been interested in all aspects of the economics of obesity—the causes, consequences, treatments. I'm fortunate to have picked this research topic at the right time. Early on, it was seen as a quirky research focus, but since obesity has become a major public health problem it's now widely recognized as an important area.
CAM: How do economists approach obesity differently from other social scientists?
JC: Anthropologists look at the role of culture in determining what you eat. And we don't get to choose our culture; we're born into it. Sociologists look at the influence of our family and our peers. In those social sciences, individuals are seen as buffeted by external forces; in economics, the role of free will, of choice, is much greater. And there's a lot of debate about this. You'll get pushback from psychologists, sociologists, and anthropologists who say, "You're born into a neighborhood and a family with this income, and you really don't have choices." But when you look at how people actually behave, they are responding to incentives.
CAM: Like what?
JC: Studies have found that even children respond to variation in food prices. You might think that there's no way—children want what they want and have no concept of a budget—but studies have shown that if you make healthy foods cheaper, children will buy more. And if you make energy-dense foods like candy and soda pop more expensive, kids will buy less. That's very powerful—that even kids, whom we don't think of as very farsighted or rational, respond to prices. This suggests specific policy solutions, like taxes. We're all hard-wired to prefer calorie-dense foods, but that doesn't mean we're all destined to be obese.
CAM: So it all comes back to studying personal choices?
JC: People typically think of economists as being conservative, but actually economics is incredibly liberal in that it allows that each of us has our own individual preferences and faces different constraints such as income. That means that I can make a different decision than you, and it's not necessarily irrational. I might really enjoy eating energy-dense foods and watching TV, and because of that I may be more likely to end up overweight or obese. I might know what the risks are, that it's going to shorten my lifespan, but I might say, "I enjoy this lifestyle." An economist would say, "OK, that's rational for him. Who am I to tell him he's living the wrong way?" That's a huge difference from the public health view, which is that people who are overweight and obese are doing something wrong, and we have to stop them.
CAM: Can you give an example?
JC: I've got two kids, and they're still very young. Before I had kids, I would go to the gym every other day. Now I don't go at all, because I don't want to be away from my kids that much. I accept that there is a trade-off. I know I'm less muscular and more flabby, and I can live with that. I think I'm making a rational decision—I value my kids more than my appearance and my short-term health. As they get older, and want to play with me less, I'll start going to the gym again.
— Beth Saulnier