The Agriculture Department programs will cost about $73 billion in fiscal 2009. They range from school milk to food stamps and the Women, Infants and Children food program.

The large price tag has prompted some critics to point to research blaming the programs as a factor in a global obesity crisis.

"USDA is not aware of any convincing evidence that school meals or other federal nutrition programs cause obesity and overweight. The evidence that does exist is mixed," Thomas O'Connor, USDA's acting deputy undersecretary for nutrition, told a House Appropriations subcommittee.

An estimated 61 million Americans are affected by the department's nutrition programs. Recently, the recession has boosted demand for assistance. A record 31.8 million people received food stamps at the latest count and other programs are at or near record levels.

Kelly Brownell, a professor at Yale University's Rudd Center for Food Policy and Obesity, said he did not believe there was sufficient evidence to show USDA's programs were leading to more obese Americans.

"I believe it comes up in the context of critics of these programs using this as an excuse for wanting to cut back," he said.

Despite widespread support for the food programs, Brownell and others said the measures have the ability to do more to curb the obesity problem.

"I believe we have lacked the coordination and long-term vision to take full advantage of their potential," said Rep. Rosa DeLauro, a Connecticut Democrat and chair of the subcommittee.

An estimated 32 percent of U.S. children fit the government's definition of being overweight and 16 percent are considered obese, putting themselves at risk for serious health problems.

President Barack Obama has a goal of ending childhood hunger by 2015. He has proposed a $1-billion-a-year increase in funding for child nutrition that would be used in part to improve access to programs and improve the nutritional quality of school meals.

Lynn Parker, a scholar at Institute of Medicine, said the environment that children are in plays a big role in contributing to their obesity. For example, having high fat or high sodium items at school sends the wrong message.