"The school environment is a special environment where having a government play a role in setting the standards for what's sold makes sense," Scott Faber, a vice president at the Grocery Manufacturers Association, told reporters.

"I think the public marketplace is a different environment," he said.

The Obama administration has launched an initiative, led by first lady Michelle Obama, to combat growing levels of obesity among children. She has urged food makers to work faster to reformulate or repackage food to make it healthier for children.

"They respect our ability to find ways to produce more products that offer consumers more choices including choices with less sodium, less sugar, less fat," said Faber.

The food industry group said its members improved the nutritional value of more than 10,000 products between 2002 and 2006 and plans in May to update that total to include changes through 2009.

A separate initiative called the Healthy Weight Commitment Foundation -- which includes many GMA members -- will announce pledges to improve the health content of its products later this month.

Obesity rates among U.S. children have doubled in the past 20 years, and almost a third of American children are either overweight or obese.

Obesity causes a host of health problems such as heart disease and diabetes and costs the United States an estimated $150 billion each year, according to U.S. federal agencies.

"We've heard from consumers and you can see this in the companies in terms of how they've changed their recipes," said Pamela Bailey, president and chief executive of GMA.

In an effort not to miss the lucrative push toward healthier foods, major food manufacturers have recently changed some popular products.

Kraft Foods, the maker of Oreo cookies and Velveeta cheese, announced it would cut sodium levels in its North American products by about 10 percent over the next two years -- eliminating more than 750 million teaspoons of salt.

PepsiCo, the world's No. 2 soft-drink maker, vowed in March to cut the levels of salt, sugar and saturated fats in its top-selling products by 2020.