Obesity remains an economic issue, Seattle obesity study finds

Ensuring access to healthy, affordable foods is a top priority in tackling the obesity epidemic in the United States. Over the course of the last six months, the Institute of Medicine, United States Department of Agriculture, The White House and First Lady Michelle Obama have taken an interest in improving access to affordable and nutritious foods.

Here in Seattle, Adam Drewnowski, UW professor of epidemiology, and his team are tackling the same issue. Remember the "fat zip codes" that predicted obesity rates from a few years ago? Drewnowski and his team were the brains behind that, as well as last summer's study which showed that grocery prices in Seattle varied greatly between one supermarket chain and another.

Now, researchers at the UW Center for Public Health Nutrition, UW Urban Form Lab and the Nutritional Sciences Program in the School of Public Health are asking: "Who buys what foods, why, where, and for how much?"

The answers might surprise you. Most studies have used distance to the nearest supermarket as the best predictor of whether people have good diets and better health. But Drewnowski and team say that's not true. "Six out of seven people shopped for food outside their immediate neighborhood," he said "The closest supermarket for most people was less than a mile away, but people chose the market that was more than three miles away." Driving further to save money on groceries is common. For that reason, physical proximity to a supermarket may not, by itself, assure a healthy diet. "Money does matter," Drewnowski said.

Areas where access to healthy affordable foods is scarce have become known as "food deserts." Seattle, however, is well-supplied with supermarkets, grocery stores, farmers markets and other vendors, said Drewnowski. "We do not see evidence of significant food deserts," he said. In comparison with other areas in the state, public transportation is also prevalent and accessible, so people can take a bus to a supermarket or grocery store with relative ease.

Researchers combined a telephone survey, modeled on the Centers for Disease Control and Prevention (CDC) Behavioral Risk Factors Surveillance System, with new geo-coding techniques and methods of spatial analysis for the new study.

Economic access has also become a primary research focus in public health nutrition, including the work by Drewnowski and team. Supermarket chains have specific demographics-consumers differ by age, education, income, health, and even obesity rates. "The county-wide obesity rate in 2007 was 19.8 percent, but our research found that the obesity rate was only four percent among Whole Foods and PCC shoppers," said Drewnowski. "Consumers who shop at most area supermarket chains have obesity rates at 25 percent and higher. Clearly, not all supermarkets are the same and economic access is determined by price."

UW researchers recently discussed the Seattle Obesity Study results at "Shopping for Health" conference, which brought together public health agencies, academicians, supermarket representatives and policymakers from Seattle, King County and Washington state. Additional findings include: