Sprawl Doesn't Cause Obesity

Body-mass index scores in most city neighborhoods differ little from those in the farthest outlying areas, the researchers said.

Their findings contradict the conventional wisdom that city dwellers are thinner because their dense, centralized environment encourages walking, while suburbanites and rural residents tend to drive to widely scattered destinations.

The lowest body-mass index scores were found among residents of inner-ring suburbs -- residential areas in the middle ranges of density and distance from the city center.

"This research responds to the suggestion that highway construction causes sprawl, and in turn, sprawl contributes to obesity," said Siim Soot, director emeritus of the Urban Transportation Center in the UIC College of Urban Planning and Public Affairs.

"Obesity is a national problem, and poor diet and insufficient exercise are recognized as the primary causes," Soot said. "But observers increasingly have pointed to our culture and our built environment as possible contributing factors -- specifically, the relationship of residential setting and urban sprawl to obesity."

The year-long study builds on earlier UIC studies showing that factors other than expressways cause urban sprawl, Soot said.

The researchers calculated body-mass indices from height and weight data on the driver's licenses of about 7 million anonymous residents in more than 300 ZIP code areas. They correlated these data to each area's population density, distance from downtown Chicago, modes of commuting, number of streets and intersections, household income, and a variety of personal and household characteristics.

Among the findings:

--Residents of high-income areas with high percentages of college-educated residents and high home values are less likely to be obese.

--Inner-ring suburbs have the lowest body-mass index scores, followed by most city neighborhoods and distant suburbs.

--The highest body-mass index scores were found in city neighborhoods with predominantly ethnic or racial minority populations.

--Use of pubic transit in commuting and ease of walking are not associated statistically with obesity.

"This analysis relies on self-reported data that is updated irregularly," Soot said. "However, we used the driver's license data because we have an enormous sample and because we have addresses. These two advantages outweigh any potential bias in the weight information."

The full report is available at http://www.utc.uic.edu/Publications/BMIReportColor1jan2006.pdf

UIC ranks among the nation's top 50 universities in federal research funding and is Chicago's largest university with 25,000 students, 12,000 faculty and staff, 15 colleges and the state's major public medical center. A hallmark of the campus is the Great Cities Commitment, through which UIC faculty, students and staff engage with community, corporate, foundation and government partners in hundreds of programs to improve the quality of life in metropolitan areas around the world.

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