Coca-Cola Sugar Hiccup: Soda Giant on the Defense

"I think we have millions of Americans trying to eat down to their level of inactivity, and it's not working well," Pate said. "I believe strongly we will have to increase the physical activity level of our population if we want to overcome the obesity epidemic that we are currently challenged by."

Coke is not the only soda company getting heat. Pepsi hired Beyonce for undisclosed millions to promote its product at the Super Bowl and in new TV ads.

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Mark Bittman, food writer for The New York Times, said the superstar is making a "bad decision" to work with the beverage company.

"She has associated herself with Michelle Obama's Let's Move campaign -- a campaign to eat better [and] move more ... and now [she is] pushing Pepsi, really quite the opposite of that," he said. "She might consider giving some or all of this money to charity."

Both Beyonce's public relations team and PepsiCo, the maker of Pepsi, declined to comment to ABC News.

A spokesman for the American Beverage Association, which represents the non-alcoholic beverage industry, told ABC News that it has partnered with Michelle Obama on her "Let's Move" campaign, as well as Bill Clinton to encourage a "meaningful impact on the complex issue of obesity."