It has always been difficult to make something out of nothing, but a new report linking America’s growing obesity problem with urban sprawl (suburban living) sets a new record for political spin. The report (Measuring the Health Effects of Sprawl), released by Smart Growth America and the Surface Transportation Policy Project, purports to demonstrate that people living in more sprawling, suburban counties are fatter than people who live in more dense central cities. Accepting, for the sake of discussion, the validity of the results (which I do not), the results fall far short of significant.

The North Carolina claims make the point. The researchers suggest that in the less sprawling counties, people walk more, which accounts for much of the doubtfully reported difference in weight. Using their formula, one can deduce that average person in the least sprawling North Carolina county (Durham, by the report’s criteria) walks barely 10 minutes more per month (20 seconds per day) than those in the state’s most sprawling county, Yadkin.

Even with their microscopic research tools, the authors find little in health effects.

In the Triangle, the report claims that residents of sprawling Franklin County residents weigh 0.5 pounds more than people who live in less sprawling Durham County.
In the Triad, less sprawling Guilford County residents are said to weigh 0.4 pounds less than those in more sprawling Randolph County. And Yadkin Country residents stand out in any crowd due to their additional 0.2 pounds (3 ounces).
In the Charlotte area, residents of less sprawling Mecklenburg County weigh 0.5 pounds less than those who live in more sprawling Union County.

The story is the similar elsewhere around the nation. Chicago dominated Cook County residents can look down on their suburban Lake County neighbors, whose slothfulness manifests itself in 0.9-pound greater weight. Or one can look at San Francisco, whose residents are a fit two pounds lighter than their counterparts in sprawling Marin County. When is the last time you saw a late night cable television commercial for a weight loss program claiming it could take off two pounds in a lifetime?

So much for manipulating the inconsequential to feign significance. Centers for Disease Control data demonstrates that obesity has skyrocketed in the United States over the past 10 years. From 1991 to 2001, obesity rose from 13.0 percent to 22.6 percent in North Carolina. By comparison, the report estimates the largest sprawl related obesity difference in North Carolina metropolitan areas at 0.9 percentage points — 1/10th of the North Carolina increase over the past 10 years. Something else is going on.

Suburbanization and sprawl did not start in the 1990s. In fact, the 1990s were the least sprawling decade since the World War II, with urban densities remaining largely unchanged. And, transit’s share of urban travel is little more miserable today than it was 10 years ago. Car usage increased less in the 1990s than in any decade since before 1940. Yet obesity increased significantly over the last decade.

There are also potentially fatal flaws in the survey design. The researchers excluded the impact of household income in their calculations. Generally, obesity tends to fall as incomes rise. Income alone, if it had been included, could have negated the results. And the “sprawl index,” concocted for each county is so skewed by New York City data that the equation developed to predict results could have been rendered useless.

But one thing is sure. Measuring the Health Effects of Sprawl falls far short of establishing any material or believable nexus between sprawl and obesity. Public policy should not rest on differences of a pound or less.