According to new study from the Perelman School of Medicine at the University of Pennsylvania, the “stop” signal prompted some to choose a lower calorie or healthier food alternative.

Researchers at the University of Pennsylvania had nearly 250 corporate employees order their food from new online cafeteria system for six weeks. When they saw a traffic light labeling on the menu, the employees ordered menu with roughly 10 percent lower calories than those who received normal menus without the traffic light label.

“Calorie labeling appears to be effective in an online environment where consumers have fewer distractions, and the simpler traffic-light labeling seems as effective as standard calorie numbers,” said lead author Eric M. VanEpps, PhD.

Study also discovered that calorie labeling had a higher impact on obese people in the study than on non obese people.

Starting from December 2016, chain restaurants and certain other retailers that sell prepared food must list calorie on their menus.

“Calorie labeling appears to be effective in an online environment where consumers have fewer distractions, and the simpler traffic-light labeling seems as effective as standard calorie numbers,” Eric VanEpps, the lead author of the study, said in a press release. “The similar effects of traffic-light and numeric labeling suggests to us that consumers are making decisions based more on which choices seem healthier than on absolute calorie numbers.”