There might be an economic cure for the nation's obesity: Hike the price of food.
Raising the price of a calorie for home consumption by 10 percent might lower the percentage of body fat in youths about 8 or 9 percent, according to research from the National Bureau of Economic Research.
"An increase in the price of a calorie regardless of its source would improve obesity outcomes," according to the working paper by Michael Grossman, Erdal Tekin and Roy Wada.
As the nation confronts an epidemic of flab, many have pointed a finger at low food prices as a cause, leading to proposals for taxes on sugary drinks, fast food and junk food, as well as reductions in farm subsidies.
The new research, which focused on youths, reinforces the idea that prices affect obesity and that raising fast food prices would help, while pushing up the prices of healthy foods, such as fruit and vegetables, might hurt.
To conduct the study, researchers used measures of body fat from the National Health and Nutrition Examination Survey, as well as the prices of 21 grocery store items - everything from a pound of Jimmy Dean sausage to a 24-ounce loaf of white bread to a 2-liter bottle of Coke. They also used prices for three fast food items: a quarter-pounder with cheese from McDonald's, a thin-crusted cheese pizza from Pizza Hut or Pizza Inn and fried chicken at KFC or Church's.
The research also showed that people from different groups - males and females, whites and non-whites - respond differently to food price increases. The price of meals in fast food restaurants, for example, influences the fat weight of males more than females; by contrast, females respond more to the price of fruits and vegetables, gaining more weight when those prices rise. The study also found that the percentage of body fat for whites is more responsive to the price of fruits and vegetables than that of non-whites.
"The price of fruits and vegetables never has a significant effect on male percentage of body fat," the authors wrote.
Such research in recent years has spurred an array of proposals to make food, or at least some foods - such as those with high sugar and fat content - more expensive. But the most direct means, economists say, is to tax calories.
Abigail Okrent, an Agriculture Department researcher, and Julian Alston, a professor at the University of California-Davis, have compared a variety of alternatives: a fat tax, a sugar tax, a calorie tax and a general food tax.
"A calorie tax would get you the biggest bang for the buck; it's the most direct way of taxing obesity," Okrent said.
There are at least a couple of problems with that option, though. Nutritionists would prefer to distinguish between "good" calories and "bad," and it might push the price of staples beyond the reach of the destitute.
"It's probably not politically feasible," Okrent said.