The U.S. Food and Drug Administration (FDA) on Tuesday issued two final rules requiring that calorie information be listed on menus and menu boards in chain restaurants, similar retail food establishments and vending machines as part of the country's efforts to fight obesity.

"Americans eat and drink about one-third of their calories away from home," FDA Commissioner Margaret Hamburg said in a statement. "These final rules will give consumers more information when they are dining out and help them lead healthier lives."

According to the FDA, the menu labeling rules apply to restaurants and similar retail food establishments if they are part of a chain of 20 or more locations, doing business under the same name and offering for sale substantially the same menu items.

More specifically, the menu labeling rules cover sit-down and fast-food restaurants, bakeries, coffee shops and restaurant-type foods in certain grocery and convenience stores.

The rules also cover take-out and delivery foods such as pizza, foods purchased at drive-through windows or places of entertainment such as movie theaters or foods that you serve yourself from a salad or hot-food bar, as well as alcoholic drinks such as cocktails when they appear on menus.

The FDA said the rules have the flexibility to enable multi- serving dishes like pizza to be labeled by the slice rather than as a whole pie.

Meanwhile, seasonal menu items offered for sale as temporary menu items, daily specials and condiments for general use typically available on a counter or table are exempt from the labeling requirements.

Calorie information on menus and menu boards will need to be clearly displayed and cannot be in smaller type than the name or price of the menu item, the FDA said. For salad bars and buffets, the calorie information must be displayed on signs near the foods.

Restaurants and similar retail food establishments have one year and vending machine operators have two years to comply with the menu labeling requirements, the U.S. agency added.