New research from Carnegie Mellon University suggests graphics on menus can be just as effective as numbers at encouraging diners to eat less.

In an effort to get consumers to lower their caloric intake, the U.S. Food and Drug Administration mandated most chain restaurants to state the number of calories that each menu item contains. However, a new study found that another popular way of indicating calorie information, an image of a green, yellow, or red traffic light, can be just as effective.

"We find that either numbers or traffic lights have the same beneficial effect when it comes to taking in fewer calories," write the authors of the study. "In our particular study, either method resulted in food choices that contained 10 percent fewer calories."

For the study, researchers conducted a field experiment in which employees at Humana, a large health-care company, were asked to place lunch orders through an online platform designed especially for the study. A control group was given no calorie information. In the experimental group, employees were given either the number of calories, a traffic light indicating the approximate number of calories (a green light, for instance, meant the fewest calories), or both.

They found that providing calorie information, either through numbers or icons such as traffic lights, encourages diners to take in fewer calories.

Although providing calorie information in the form of numbers may seem like the best option, policymakers should consider that not all consumers are adept at interpreting numbers.

"For those consumers, traffic light labels can communicate basic 'eat this, not that' information regardless of their understanding of the underlying nutrients or ability to use numeric information," the authors write.

The findings are detailed in the Journal of Public Policy and Marketing.