Why are we getting fatter?

Apparently the number one reason might be that we're no longer smoking:

As the country sheds manufacturing jobs and more Americans move from blue-collar positions to white, jobs are becoming more and more sedentary. With the economy in tatters, food stamp use (and, with it, the consumption of unhealthy foods) is on the rise. But there's another factor contributing to our weight gain that is often overlooked: Smoking.

Smokers are less likely to be obese. And the declining use of cigarettes across the country -- due to both tightening pocketbooks and new laws (thanks, Mayor Bloomberg) -- accounts for a bigger increase in the obesity rate in the U.S. than any other factor, according to paper authors Charles L. Baum and Shin-Yi Chou, who have both written with some frequency on the economics of obesity.