While just 15 percent of people who buy fast-food in New York City read the calorie information required on menus, customers using the information tended to buy foods with fewer calories, the study by the New York Health Department found.
New York has required chain restaurants with 15 or more locations nationally to print calorie information on menus and menu boards since 2008, WebMD reported Tuesday.
People who reported using the information labels purchased 106 fewer calories than customers who did not use or see them, the study found.
The findings come as U.K. restaurants prepare to introduce a similar scheme, the BBC reported.
Thirty-two companies have agreed to display calorie information in their U.K. outlets, including McDonald's and KFC.
"One in six meals in the United Kingdom eaten away from home so it's essential we know what's in the food we're buying in restaurants and cafes," Beatrice Brooke of the British Heart Foundation said.
"The New York research shows us just how valuable calorie labeling in fast food restaurants can be."