The Food and Drug Administration is ready to publish new rules that will require restaurant chains to show the calorie counts for all the items on their menus.

The new requirement, which is a part of the 2010 Affordable Care Act, will establish a country-wide standard that applies to restaurant chains that have 20 or more branches. The requirement will also apply to operators of vending machines, amusements parks and movie theaters.

The rules state that calories for each food item should be displayed on all of a restaurant's menus and menu boards. Restaurants should also be able to provide other nutritional information to customers regarding the food that they serve when requested, including data on total fat, calories from fat, trans fat, saturated fat, sodium, cholesterol, fiber, total carbohydrates, protein and sugars.

The food that will be covered by the new rule include meals eaten at sit-down restaurants, food bought from take-out counters, bakery products, ice cream and pizza. Seasonal food, such as Thanksgiving meals, daily specials and the usual condiments will not be affected.

"Obesity is a national epidemic that affects millions of Americans," said Margaret Hamburg, the commissioner of the FDA, adding that Americans consume about one-third of their daily calorie intake while away from their homes.

The FDA's first proposal of the rule was made in 2011, but changes have been made since then after the consideration of over 1,000 comments that the agency received from consumer, public health advocates and industry representatives.

Changes to the original proposal include a narrower scope of the food covered by the rule to focus on items served in restaurants. Other kinds of food, such as meat bought at the groceries, will not be affected.

"We believe that the Food and Drug Administration has positively addressed the areas of greatest concern," said National Restaurant Association CEO Dawn Sweeney, representing how the industry lauded the changes that the agency made to the original proposal.

The National Restaurant Association represents almost 1,000,000 branches of restaurants and food service companies.

Some companies have already previously started displaying calorie information on their food items. The first company to voluntarily do so was Panera Bread in 2010, followed by McDonald's and Starbucks.

To be able to determine the calorie counts for menu items, restaurants could retrieve information from several databases, food labels and cookbooks for the information.

Restaurants will have one year to carry out their compliance of the new requirement after it has been published in the Federal Register. Operators of vending machines, however, will be given two years.