Diners are placing fewer orders for fries and sugary drinks at restaurants, giving a boost to those that sell more low-calorie items.

An analysis of 21 fast-food and sit-down restaurant chains between 2006 and 2011 found that lower-calorie food and beverages fueled restaurant chains' growth. The study was funded by the Robert Wood Johnson Foundation and conducted by the Hudson Institute, a policy-research organization.

The study found that restaurants that increased lower-calorie servings experienced an average 5.5% increase in same-store sales. That compared with a 5.5% decrease among chains selling fewer lower-calorie servings.

"The bottom line is, if restaurants don't get more aggressive behind these low-calorie products, they're leaving sales on the table," said Henry Cardello, director of the Hudson Institute's Obesity Solutions Initiative and lead author of the report. "It's a business imperative."

Cardello and his colleagues worked with the Nutrition Coordinating Center at the University of Minnesota to develop the calorie criteria used to assess menu items. The findings might make restaurant chains feel better about efforts around the U.S. to get them to post calorie information.

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