Restaurants that offered more lower-calorie services saw a 9 percent increase in food and beverage sales from 2006 to 2011, while restaurants that didn't saw sales drop by 16 percent.
The researchers defined lower calorie as a main item with fewer than 500 calories, a side dish with fewer than 150 calories, and a beverage below 50 calories for an eight-ounce serving.
"You go to McDonald's and get a plain old burger, and you don't get many calories," says Hank Cardello, a senior fellow at the Hudson Institute and author of the report. It was funded by the Robert Wood Johnson Foundation.
A former food industry executive at companies like Coca-Cola and General Mills, Cardello is of the belief that badgering people about eating healthy isn't necessarily the only way — or the best way — to solve the nation's obesity crisis.
"We found some good performance in restaurants that were selling smaller-portion chicken sandwiches," Cardello says. Even if that's a fried chicken sandwich, he notes, smaller means fewer calories. And for the restaurants, "You don't give up profits by doing that."
New federal regulations requiring chain restaurants to post calorie counts will take effect next year, but some, including McDonald's, already provide that information. Earlier studies have found that posted calorie counts don't drive people to make better choices, and that they can actually be so confusing as to be useless. But this study suggests that people are starting to pay attention.
Cardello hopes the dollar figures will get restaurateurs to pay attention, too.
"The restaurant industry as a whole is a very show-me industry; show me why I should change." He knows he's not going to convert the chains to being public-health advocates. but now, the chains will know that they should "get with the program, or you leave money on the table."
Editor's Note: The Robert Wood Johnson Foundation also funds coverage of health care on NPR.