Tracking the Environmental Causes of Obesity

October 15, 2002

Heather Heilman

Obesity is the fastest-growing health epidemic in America, and relying on individual willpower is not an effective way of fighting it, according to Tulane researchers who are examining the environmental causes of the epidemic. The problem is greatest in low-income communities.

About 28 percent of Americans are obese; among poor black women that number rises to more than 50 percent. About 70 percent of the patients at Charity Hospital are clinically obese, and residents at the hospital feel helpless to change that, according to a survey conducted by Karen DeSalvo, chief of internal medicine, and Jason Block.

"They have pretty negative attitudes about their ability to treat obesity," said Block, a fourth-year student at Tulane University School of Medicine. "A fair amount of them responded that trying to treat obesity is futile."

Part of the problem is that we look at obesity as an individual problem, but we live in a society that promotes overeating and physical inactivity and makes it hard to stay thin.

"If we're going to affect the problem, we're going to have to look at what we do in our environment that causes people to be more at risk for obesity," Block said.

He and DeSalvo, along with a colleague at Louisiana State University, have recently completed a pilot study looking at fast-food restaurants in Orleans Parish. They mapped out the locations of all the fast-food restaurants in the city, including 14 national chains and Bud's Broilers, and were not surprised to find that there was a strong correlation between density of fast-food outlets and the percentage of the neighborhood population that is African-American.

Now they're anticipating expanding the study into Jefferson Parish, where they will look directly at the association between fast-food density and rates of obesity. Of course, fast food is not the single-handed cause of obesity, despite a lawsuit filed against four fast food chains in New York this summer.
Nevertheless, between 1977 and 1995, Americans' consumption of fast food tripled at the same time that obesity rates were rising. And if hamburger and fried-chicken outlets are concentrated in a neighborhood where instead of supermarkets there are only convenience stores offering overpriced snack foods, where many people lack transportation to stores outside of the neighborhood, and where an evening spent watching television is safer than a walk around the block, then the outlets are likely to do a booming business and to have a negative impact on the community's health.

Tom Farley, chair of community health sciences, agrees that the only way to fight the accelerating rate of obesity is by making changes to our environment.

"Obesity is a growing epidemic," he said. "Genetically, some people are more likely to get obese than others, but that doesn't explain why the whole population has gotten fatter in the last 30 years. It's the environmental changes that have made the difference."

A few years ago, he did a pilot study looking at food availability in New Orleans' Central City. The idea was to do a before-and-after comparison to see how the proposed Albertson's supermarket would affect how people in the neighborhood ate. The new supermarket has yet to appear, but in the meantime his survey indicated that the convenience stores allot about five times as much shelf space to snack foods as they do to fresh fruits and vegetables. But Farley believes lack of physical activity is an even bigger contributor to the problem.

"In poor neighborhoods, for fear of crime and traffic, people are more likely to be in their houses watching television, " Farley said. "And watching television has a very strong relationship with obesity."

While watching television, the body's metabolism drops to close to the level of sleeping. Even sitting and talking with friends burns 35 more calories per hour than watching TV. It would be easier to get people off the couch if there were safe playgrounds for kids to play in and safe neighborhoods for people to walk in.

"We need public policy that makes it easier for people to get physical activity and that makes our environment less full of high-calorie, high-fat food," Farley said. "There are all sorts of levels where policies could be put in place if we would just think about that approach. Otherwise, the tendency will be for the epidemic to get worse."

Heather Heilman may be reached at

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