Watching the Detectives

Epidemiologists are hot on the trail of the obesity pathogen


West Virginia's status as the third-fattest state, confirmed in a recent report from the Trust for America's Health, gives new meaning to the phrase "Mountain Mama" in John Denver's Blue Ridge paean "Country Roads." For the morbidity and mortality experts at the Centers for Disease Control and Prevention, it also poses a puzzle: Why are West Virginians so fat?

I'll hazard a guess and say it's because they eat too much. But the CDC is not satisfied with layman's explanations. A few months ago, it sent a crack team of investigators to hunt down the source of West Virginia's obesity outbreak.

According to The New York Times, the CDC's "disease detectives" spent three weeks in Gilmer County and Clarksburg, asking the tough questions that needed to be asked. At local schools they demanded to know if "at least one or two appealing fruits and vegetables" were offered every day in the cafeteria, and if the administration would consider replacing regular sour cream with a low-fat version.

In local workplaces, they asked whether fruit juice and bottled water were available in the vending machines, and whether employees could get extra time for their lunch breaks if they promised to spend it walking. They surveyed the produce and milk selections in "random grocery stores and restaurants." They looked for sidewalks and checked them for cracks.

Upon hearing about the CDC's epidemiological odyssey, Florida State University statistics professor Daniel McGee "burst out laughing," the Times reported. "My God," he said, "what a strange thing to do." Another statistician, the University of Wisconsin's David DeMets, was similarly dismissive, saying "we get a lot of false positives from that kind of investigation," since there's no way to tell whether any given factor contributes to obesity or, if so, to what extent.

Yet the CDC, which began life as an agency devoted to fighting malaria in the South and today is determined to eradicate obesity there, is simply following the logic of its own rhetoric. Faced with a nationwide "epidemic" that is especially pronounced in Southern states, it is looking for the vectors that transmit the "disease."

Once the government understands these vectors, the CDC assumes, it can control obesity, just as malaria can be controlled by draining mosquito-breeding swamps and cholera can be controlled by removing the pump handles from contaminated wells. This approach would make perfect sense if obesity were caused by microorganisms. But since obesity is caused by certain patterns of behavior, themselves subject to myriad influences, this is one case the disease detectives are not likely to solve.

That has not stopped them from rounding up the usual suspects. A study in the September issue of the American Journal of Public Health, for instance, warns about fast food "clustering" near schools. "The concentration of fast-food restaurants around schools within a short walking distance for students is an important public health concern," the researchers declare, "in that it represents a deleterious influence in the food environment that may undermine public health efforts to improve nutritional behaviors in young people."

Since "public health" appears twice in a sentence that also mentions the environment, this must be serious. But what exactly are they talking about?

The study found that 80 percent of primary and secondary schools in Chicago are located within 800 meters of a fast-food outlet (about a 10-minute walk) and 35 percent are only 400 meters away. "A significantly greater number of fast-food restaurants are located within a short distance from schools than would be expected if there were no spatial dependence," the authors report.

Although the Center for Science in the Public Interest immediately cited the study as evidence that the "food industry targets children," the simplest explanation is that fast food restaurants tend to be located in commercial areas with many potential customers. There was no sign of "clustering" around schools in noncommercial areas.

In any case, the researchers present no evidence that having a McDonald's or Subway near school makes students fatter. They nevertheless close their article by suggesting fast-food-free zones around schools that would "remove noxious elements in the food environments that schoolchildren are exposed to every day"—and, incidentally, limit the lunch options of all the adults who happen to work or shop nearby.

This is the sort of policy—coercive, choice-restricting, and almost certainly ineffective—that comes from treating behavior like a contagious disease.