Pricier Gas? Flatter Abs.

Greg Mankiw points to a new working paper quantifying the relationship between gas prices and obesity.

Charles Courtemanche of Washington University in St. Louis finds that 13 percent of the recent rise in obesity from 1979 to 2004 is a result of the drop in gas prices during that period and that a $1 rise in gas prices would cut obesity by 15 percent in the U.S., saving 16,000 lives and $17 billion per year.

How does this work?

Courtemanche postulates that, when gas prices are high, some people have to substitute walking or taking public transportation for driving, cut back eating dinner at restaurants (which is generally less healthy than eating at home), and/or eat less food at home because more money is spend on gas.

Another interesting result from the paper:

A rise in gas prices appears to increase the frequency of hamburger consumption...People do not consume fewer hamburgers when gas prices rise, but they cook their own burgers instead of driving to Ruby Tuesday for a Colossal Burger, inevitably leading to the consumption of far fewer calories.

So, would a gas tax improve the nation's obesity crisis?

Not quite, writes Courtemanche:

It is possible that policies designed to alter gas price in such a way as to induce healthier eating and exercise decisions may improve social welfare. However, since a reduction in income increases weight, we should take care not to implement policies that would leave people poorer. For example, an increase in gasoline taxes could be accompanied by mass transit subsidies or even a reduction in payroll taxes.