Sprawl and Obesity: NYC as a case study

The City Data web page contains, among other things, county-by-county statistics on obesity.   Because each New York borough is a county, I thought that looking at New York might be more informative than looking at other metro areas where a county can include a wide range of cities and suburbs.

Manhattan (New York County) is especially instructive.  In Manhattan, the obesity rate is only 15.4 percent- well below the state average of 23.8 percent.

Suburban areas suffer somewhat more from obesity: inner-ring Westchester County, which includes many of the region's more affluent suburbs, has an obesity rate of only 19.1 percent.   Nassau County's obesity rate is 20.9 percent, while further-out suburbs (Suffolk, Duchess, Putnam, and Rockland Counties) have obesity rates in the 23-25 percent range. 

But on the other hand, New York's outer boroughs have obesity rates as high as those of the suburbs: the Bronx's obesity rate is over 25 percent, and the other three boroughs (Brooklyn, Queens, Staten Island) have obesity rates in the 23-25 percent range. What's going on?

Here's my educated guess: both poverty and sprawl correlate with obesity.  Manhattan is richer than the other boroughs and pedestrian-oriented, and thus has the least obesity.  The outer suburbs have sprawl but wealth (and thus moderate levels of obesity) and the outer boroughs are less sprawling than the suburbs and poorer than Manhattan (and thus also an equivalent amount of obesity).  Inner ring suburbs are as well off as outer suburbs and less car dependent than outer suburbs, and thus have less obesity than outer suburbs. In other words, obesity, at least in New York, is a function of wealth (or the lack thereof) and sprawl.

No rural place in New York is as poor as the Bronx- but nationwide the highest levels of obesity are in poor counties and the rural South.  For example, Greene County, Alabama has only 14 people per square mile, a 34 percent poverty rate, and a 43 percent obesity rate- a perfect storm of car dependence and poverty.