McDonald’s Corp., which has been criticized for marketing calorie- and fat-laden food to children, said on Wednesday it is partnering with leading biomedical scientists to fund research and programs aimed at preventing childhood obesity.

The world’s biggest fast-food company is donating $2 million to the La Jolla, California-based Scripps Institute, the first time it has ever directly funded scientific research, said President and Chief Operating Officer Ralph Alvarez.

“Everything that we keep on seeing is the whole issue of childhood obesity and the early onset of type 2 diabetes has grown exponentially,” Alvarez said in an interview on Tuesday. “We felt we needed to get greater education in this area.”

The move comes as McDonald’s has been working to fend off high-profile accusations that the company is partly to blame for the 16 percent of U.S. children and adolescents who are overweight or obese.

In the last two years, McDonald’s has undertaken a campaign to promote what it calls balanced, active lifestyles by eliminating “Super Size” portions of French fries and soft drinks, and by promoting physical activity to its customers in its marketing and advertising.

The campaign followed the 2002 book “Fast Food Nation,” which criticized the fast-food industry, and the 2004 release of the film “Super Size Me” - a cautionary tale about the dangers of eating too much fast food. A film version of “Fast Food Nation” will hit theaters later this year.

But the irony of a company known for selling greasy hamburgers throwing its weight behind obesity research does not bother Alvarez, who said McDonald’s is thinking long-term.

“Ironic or not we’re going to make a difference,” he said. “You won’t see those benefits short-term, in one to three years, because habits change over time. But as a major restaurant company, we need to be on the cutting edge of what’s happening.”

One expert said McDonald’s move was encouraging, but added that the fast-food chain still has more work to do to address its role in the obesity epidemic.

“It’s good that they are funding useful medical research, but that doesn’t absolve them of their responsibility to serve nutritious food to children,” said Daniel Borochoff, president of the American Institute of Philanthropy, a Chicago-based charity watchdog group.

According to Alvarez, half of the company’s donation will support the institute’s research and the other half will fund yet-undetermined outreach programs that could include screening for obesity-related type 2 diabetes in poor neighborhoods or supporting education programs in underfunded schools.

Katja Van Herle, a physician who leads Scripps’ community health education efforts, said the institute approached McDonald’s about the partnership in part because it has been impressed by the changes the company has made in recent years.

“It was a funny union,” she said in an interview. “This is a little bit strange, but let us help them roll out their story a little bit. They are very much in line with changing.”