Counting calories at the vending machine will be a lot easier next year — at least if you’re buying beverages.

Under increasing criticism that their products contribute to the nation’s expanding waistline, the major soft drink companies, including Atlanta-based Coca-Cola, plan to launch a “Calories Count Vending Program” in 2013 that will focus on promoting lower-calorie products at vending machines

The effort, which will begin in municipal buildings in Chicago and San Antonio in January before being rolled out elsewhere, will increase the availability of low-calorie beverages in the machines, display messages such as “Calories Count — Try a Low-Calorie Beverage” and add labels disclosing calorie counts to vending buttons.

Buyers who take the time to look will learn, for instance, that a 20-ounce regular Coke has 240 calories, while a 16.9-ounce Minute Maid Light Lemonade has 10.

San Antonio and Chicago also are getting $5 million from the American Beverage Association Foundation, which is supporting the program, for a “wellness challenge” between municipal employees in the two cities.

“This appears to be an attempt by the industry to start an initiative — not just to make diet and low-calorie products available — but also to try and motivate consumers to buy and consume more diet and low-calorie products, i.e., to shift consumer behavior,” said John Sicher, editor and publisher of Beverage Digest, which first reported the move.

Critics of the soft drink industry have for years blamed part of the country’s obesity epidemic on sugary drink consumption. Last month, New York City’s board of health approved controversial restrictions Mayor Michael Bloomberg put in place over the summer that forbid Big Apple restaurants, movie theaters and delis from selling sugary drinks in sizes larger than 16 ounces. That ban begins in March.

“Our support of the Chicago and San Antonio Wellness Challenge, and the new Calories Count Vending Program is another bold step in our efforts to help people understand the importance of energy balance,” Steve Cahillane, president and chief executive officer of Coca-Cola Refreshments, said in a release.

Al Carey, Chief Executive Officer of Pepsi Americas Beverages, told Beverage Digest, “We are taking the obesity challenge seriously, and consumers will see several meaningful examples of this in the upcoming year.”