And before you start commenting "correlation does not imply causation", consider that it makes a great deal of sense. Blogger Felix Salmon calls it the Urban Diet, noting that people who don't have a car can't fill their fridges with a ton of food, and have to give a lot more thought to what they eat. (Not to mention the fact that they walk and bike more)
Cheap Gas Makes You Fat
Felix Salmon notes that people who live in dense urban centers have more and healtier options:
Dense urban centers also tend to offer much more expensive dining options. Sure, you can find fast food if you want it. But the fast food is surrounded by restaurants you actually want to go to, and since they're just as convenient, you don't have the "no choice" excuse that you have when you stop off next to the freeway. So you gravitate to the more expensive (and generally intrinsically healthier) options. And as any economist will tell you, the amount you consume goes down as the price goes up.
The Government Makes You Fat
Of course, he got called elitist by auto industry writer Matthew DeBord:
Salmon makes it sound as if the average American eats primarily at off-the-freeway fast-food joints in between trips to the supermarket to fill their car with huge amounts of groceries. They nourish themselves by "absent-mindedly shovelling down an unknown quantity of something random while watching the TV.
Where You Live Makes You Fat
Ryan Avent leaps to Salmon's defense.
But the bottom line is that there is a very strong correlation between living in sprawl and being obese. And while it isn't necessarily the case that sprawl makes people fat, it is the case that obese people move to the burbs because it's so easy to be fat there, what with the not having to walk and the many drive through restaurants and so on.
Being Surrounded by Fast Food Restaurants Makes You Fat.
It is all a big conspiracy; the automobile created suburban sprawl, bigger and fuller fridges, the proliferation of fast food restaurants and the decline in the use of bikes. The system is rigged to put people in cars and take them to Wal-Mart for cheap high-fat food and McDonalds for more, faster. It isn't elitism, it is reality.
More: What Makes You Fat?