(Reuters) - Many restaurants, supermarkets, convenience stores and movie theaters across the United States are required starting on Monday to clearly display food calorie counts as part of a push to trim expanding American waistlines and control healthcare costs.

Almost 37 percent of U.S. adults are obese, according to the U.S. Centers for Disease Control and Prevention. Obesity raises the risk of preventable, life-threatening illnesses - including heart disease, stroke, type 2 diabetes and certain types of cancer - and is responsible for billions of dollars in annual healthcare costs.

Americans consume one-third of their calories away from home and proponents of the rule, more than 15 years in the making, say it gives people information to make healthier dietary choices.

“Menu labeling allows people an easy way to cut hundreds of calories or more with simple, split-second decisions,” said Margo Wootan, vice president for nutrition at the nonprofit Center for Science in the Public Interest, or CSPI, a leading proponent of calorie disclosure.

A recent review of nearly 30 studies from the Cochrane Collaboration nonprofit public interest group found that menu labeling helped people reduce calories by about 50 calories per meal, on average, according to CSPI. Menu labeling also has been shown to spur restaurants to reduce the calories in their foods, the group said.

The rule - part of the Affordable Care Act of 2010, popularly known as Obamacare - affects restaurants, grocery stores and other food sellers with 20 or more locations that sell ready-to-eat foods.

The rule also requires calorie labeling on more than 99 percent of the nation’s 5 million to 6 million vending machines.

The U.S. Food and Drug Administration last year extended the date for national compliance by a year.

Chains like Panera Bread Co, McDonald’s Corp and Starbucks Corp have been displaying such information for years in compliance with rules set by New York City, the state of California and other jurisdictions.

Opponents to the rule included companies like Domino’s Pizza Inc and industry groups such as the Food Marketing Institute, or FMI, which represents food retailers and wholesalers.

“We are trying to make lemonade out of the lemons FDA presented,” Jennifer Hatcher, the FMI’s chief public policy officer, said in a statement. FMI and other opponents argued that the rule piled additional costs and liability risks on businesses.