NEW YORK -- As criticism of sugary sodas intensifies, Coke, Pepsi and Dr Pepper are rolling out new vending machines that will put calorie counts right at your fingertips.

The move comes ahead of a regulation that would require restaurant chains and vending machines to post the information as early as next year, although the specifics for complying with the requirement are still being worked out.

"They're seeing the writing on the wall and want to say that it's corporate responsibility," said Mike Jacobson, executive director of the Center for Science in the Public Interest, which advocates for food safety and nutrition.

Still, he noted that it was an important step forward. "Currently, people don't think about calories when they go up to a vending machine," he said. "Having the calories right on the button will help them make choices."

The American Beverage Association, which represents Coca-Cola Co., PepsiCo Inc. and Dr Pepper Snapple Group Inc., said the calorie counts will be on the buttons people press to select a drink. Vending machines will also feature small decals, such as "Calories Count: Check Then Choose."

The vending machines will launch in Chicago and San Antonio municipal buildings in 2013 before appearing nationally.

Without providing specifics, the American Beverage Association said the machines will also boost the availability of lower- and zero-calorie drinks.

"We have market research that says consumers really like this -- they like choice, they like the ability to make choices," said Susan Neely, president of the industry group.

A mockup of a new machine provided by Coca-Cola showed 20-ounce bottles of its flagship drink and Sprite inside vending machines, with labels on the buttons stating "240 calories."

The soda industry has been under fire for fueling rising obesity rates. Last month, New York City approved a first-in-the-nation plan to prohibit the sale of sugary drinks of more than 16 ounces in the city's restaurants, movie theaters and stadiums.

Notably, the beverage industry fought aggressively to fight the ban and hasn't ruled out taking legal action to stop it from taking effect this spring.

This November, voters in Richmond, Calif., will also decide whether to approve a penny-per-ounce tax on sugary drinks.

The decision to post calorie information follows the Supreme Court's decision this summer to uphold President Obama's health-care overhaul, which includes a regulation that would require restaurant chains and with more than 20 locations and vending operators with more than 20 machines to post calorie information.

McDonald's Corp. also announced last month that it would begin posting calorie information on its menus nationwide. Like the soda industry, the fast-food giant said it was a voluntary decision and not spurred by the pending requirement.

In addition to public health concerns, soft drink makers are dealing with shifting consumer habits. Soda consumption per person has been declining in the U.S. since 1998, according to the Beverage Digest. The decline is partly the result of the growing number of options such as flavored waters, bottled teas and sports drinks -- which Coke, Pepsi and Dr Pepper also make.

As a result, Coke, Pepsi and Dr Pepper are focusing on developing more diet drinks, as well as expanding into other drinks to reduce their reliance on sodas.

There is no timetable for when all vending machines will be converted. Coke, Pepsi and Dr Pepper often work with third-party operators to provide drinks in vending machines; Neely said the companies will work with those outside operators to convert all machines over time.

Vending machines account for about 13 percent of sales volume, a figure that has remained relatively unchanged in recent years, according to Beverage Digest.

Soda consumption is often identified for playing a role in rising obesity rates, although other factors such as a lack of physical activity and overeating also contribute.

In September, the New England Journal of Medicine published a decades-long study of more than 33,000 Americans that showed sugary beverages interact with genes that affect weight, meaning they are especially harmful to people who are hereditarily predisposed to weight gain.

Bonnie Sashin, a communications director for a nonprofit organization in Brookline, Mass., says she stays away from sugary drinks, limiting herself to a can of Diet Dr Pepper or Diet Coke about twice a month. But she thought the move to display calorie information on vending machines was a positive development.

"Anything that helps us be more educated about calories is a good thing," Sashin said.