Coca-Cola became one of the world’s most powerful brands by equating its soft drinks with happiness. Now it’s taking to the airwaves for the first time to address a growing cloud over the industry: obesity.

The Atlanta-based company on Monday began begin airing a two-minute spot during the highest-rated shows on CNN, Fox News and MSNBC in hopes of flexing its marketing muscle in the debate over sodas and their impact on public health. The ad lays out Coca-Cola’s record of providing drinks with fewer calories and notes that weight gain is the result of consuming too many calories of any kind — not just soda.

For Coca-Cola, the world’s No. 1 beverage company, the ads reflect the mounting pressures on the broader industry. Later this year, New York City is set to enact a first-in-the-nation cap on the size of soft drinks sold at restaurants, movie theaters and sports arenas. The mayor of Cambridge, Mass., has already introduced a similar measure, saying she was inspired by New York’s move.

Even when PepsiCo Inc., the No. 2 soda maker, recently signed a wide-ranging endorsement deal with pop singer Beyonce, critics called for her to drop the contract or donate the funds to health initiatives.

New research in the past year also suggests that sugary drinks cause people to pack on the pounds independent of other behavior. A decades-long study involving more than 33,000 Americans, for example, suggested that drinking sugary beverages interacts with genes that affect weight and enhances a person’s risk of obesity beyond what it would be from heredity alone.

Michael Jacobson, executive director for the Center for Science in the Public Interest, was skeptical about Coca-Cola’s ads and said the company would stop fighting soda taxes if it was serious about helping reduce obesity.

“It looks like a page out of damage control 101,” he said. “They’re trying to disarm the public.”

The group has been critical of the soft drink industry and last year released a video parodying Coke’s famous polar bears becoming plagued with diabetes and other health problems.

Coca-Cola said its ads aren’t a reaction to negative public sentiment. Instead, the idea is to raise awareness about its lower-calorie drinks and plans for the coming months, said Stuart Kronauge, general manager of sparkling beverages for Coca-Cola North America.

“There’s an important conversation going on about obesity out there, and we want to be a part of the conversation,” she said.

In the ad, a narrator notes that obesity “concerns all of us” but that people can make a difference when they “come together.” The spot was produced by the ad agencies Brighthouse and Citizen2 and is intended to tout Coca-Cola’s corporate responsibility to cable news viewers.

Another ad, which will run later this week during “American Idol” and before the Super Bowl, is much more reminiscent of the catchy, upbeat advertising people have come to expect from Coca-Cola. It features a montage of activities that add up to burning off the “140 happy calories” in a can of Coke: walking a dog, dancing, sharing a laugh with friends and doing a victory dance after bowling a strike.

The 30-second ad, a version of which ran in Brazil last month, is intended to address confusion about the number of calories in soda, said Diana Garza Ciarlante, a spokeswoman for Coca-Cola Co. She said the company’s consumer research showed people mistakenly thought there were as many as 900 calories in a can of soda.

The company declined to say how much it was spending on the commercials, which it started putting together last summer. It also declined to give details on its plans for the year ahead. But among the options under consideration is putting the amount of activity needed to burn off the calories in a drink on cans and bottles.

The company noted that it already puts calorie counts on the front of its cans and bottles. Last year, it also started posting calorie information on its vending machines ahead of a regulation that will require soda companies to do so by 2014.

Coca-Cola’s changing business reflects the public concern over the calories in soda. In North America, all the growth in its soda unit over the past 15 years has come from low- and no-calorie drinks, such as Coke Zero. Diet sodas now account for nearly a third of its sales in the U.S. and Canada. Other beverages such as sports drinks and bottled water are also fueling growth.

Even with the growing popularity of diet sodas, however, overall soda consumption in the U.S. has declined steadily since 1998, according to the industry tracker Beverage Digest.

John Sicher, the publisher of Beverage Digest, noted that the industry “put its head in the sand” when obesity and soft drinks first started becoming an issue more than a decade ago. Now, he said Coca-Cola is looking to position itself in the public debate rather than being defined by adversaries.