NEW YORK >> Disney says its programming will no longer be sponsored by junk food.

The Walt Disney Co. said Tuesday that it will become the first major media company to ban such ads for its TV channels, radio stations and websites intended for children. That means kids watching Saturday morning kids’ shows on the company’s ABC network will no longer see ads for fast foods and sugary cereals that don’t meet Disney’s nutrition standards.

The guidelines won’t go into effect until 2015 because of existing advertising agreements.

First Lady Michelle Obama called the announcement a “game changer” in a statement.

“With this new initiative, Disney is doing what no major media company has ever done before in the U.S. — and what I hope every company will do going forward,” Obama said.

Disney sais its guidelines are aligned with federal standards to promote the consumption of fruits and vegetables and reduce the intake of sodium, sugar and saturated fat.

The company also introduced its “Mickey Check” seal of approval for nutritious foods sold in stores, online and at its parks and resorts.

“The emotional connection kids have to our characters and stories gives us a unique opportunity to continue to inspire and encourage them to lead healthier lives,” Disney CEO Robert Iger said in a statement.

Public health and childhood obesity experts cautioned that the effectiveness of any ban will be in how junk food is defined by the company. Previous attempts by the food industry to regulate marketing to children have been criticized as being too generous in which products were allowed.

But Aviva Must, chairwoman of the Department of Public Health and Community Medicine at Tufts School of Medicine, said Disney could succeed where government thus far has made little progress.

“There seems to be limited taste for government regulation,” said Must, who has studied childhood obesity for decades. “So I think a large company like Disney taking a stand and putting in a policy with teeth is a good step.”

Studies have long established a direct link between junk-food advertisements on television and childhood obesity, and a legitimate ban could have far-reaching public health effects, said Dr. David Ludwig, director of the New Balance Foundation Obesity Prevention Center at Boston Children’s Hospital.

“Elimination of junk-food advertisements will not make television viewing a physically healthy activity,” he said. “But elimination of advertisements will substantially reduce the harm of television viewing in childhood.”