I love it when research ends up being cycling advocacy. Jeff points to an article in the Seattle Times about how bad suburbs are for you. It contains these comments:

People who live in newer suburban neighborhoods are more likely to travel by car ? and less likely to go anywhere on foot or by bike ? than residents of traditional pre-World War II neighborhoods, Frank found.

[…]

By catering so slavishly to the automobile and discouraging walking, biking and transit, they say, suburbia has inadvertently promoted sloth. A nation that has become increasingly suburban also has become increasingly sedentary, more prone to obesity, diabetes and heart disease.

Of course, they should correlate this study with income to get a better picture of what is going on.