A new rule demanding New York chain restaurants to attach calorie information to their menus was implemented on Friday, for the first time in the U.S.

Customers of big fast-food chains in New York will at last find out what the products they eat really contain, in spite of the fact that they may not be pleased with some facts. For instance, according to the Associated Press, a Big Mac, medium fries and a medium soda sum up approximately 1,130 calories.

After several months of rejection, the chain restaurants began to apply the rule and post calorie details on the menus.

McDonald's and Burger King were two companies that released new menu boards on Friday by making the required information available and displaying it above the cash registers in franchises throughout the city.

The demand belongs to an anti-obesity campaign that has also comprised a new citywide ban on artificial fats that are in the composition of restaurant food. The regulation was first approved two years ago but was withdrawn after a court battle rejected the original version.

Cathy Nonas, director of the health department's physical activity and nutrition program, said some chains postponed the display of the required the data because they feared customers would avoid eating certain products.

Dietary advice for adults suggests about 2,000 calories a day, depending on age, gender and activity.

The new rule is applied only to restaurants that offer standardized portion sizes and own over 15 locations nationwide.