Tuesday, August 23, 2005

Obesity and Sprawl

The New York Times reports new facts today about obesity. About 24.5 percent of American adults are obese, the report said, and in 12 states more than a quarter of all adults are obese, Mississippi, Alabama, West Virginia, Louisiana, Tennessee, Arkansas, Texas, Michigan, Kentucky, Indiana, Ohio and South Carolina. The states with the smallest percentage of obese adults are Colorado, Massachusetts, Rhode Island, Connecticut, Vermont and Montana.

Here is a map presenting the current data.

Some public health officials have blamed suburbanization as a leading cause of this trend. What would be convincing evidence that sprawl makes us fat? Ideally, we would want to randomly assign people to different population densities and weigh them 12 months from now. Suburbanites do drive more than urbanites. But suburban areas have more golf courses, tennis courts, basketball courts and easy access to other recreational facilities. Ideally, a study would collect detailed time surveys to see what suburbanites and urbanites do all day long. I have trouble believing that suburbia "causes" people to gain weight. Instead, I would argue that it is self selection due to the urban marriage market. Many urbanites are singles. If I watched TV, I could name many shows ranging from Friends to Seinfeld presenting young people without children who are mingling. Suburbia self selects married people with young children. As I've recently learned, children are quite time consuming and from personal experience I've seen that I now exercise less than I used to.

A more interesting explanation for the recent rise in obesity comes from behavioral economics. Many behavioral researchers make the point that we all have self control problems. We all have "cravings" for ice cream and other munchies. In the past, it was difficult to satisfy these cravings. Transportation costs were higher. We'd have to bake our own cookies or catch a bus to some store. Now, in this car age with easy access to 7-11 and other food vendors, we can too easily satisfy our cravings. Students have dorm room fridges and they aren't filled with fruits and veggies. While this is satisfying in the short run, in the long run we get fat. Put simply, we are now "too close" to our calories. An obvious addditional factor that has been well documented is that food producers have been too productive at producing "super sized" cheap unhealthy food. If people didn't have self control problems, this would be a "good thing". We would have access to greater variety of foods and face lower prices at the market.

Are there any policy implications here? Do you support a potato chip tax?