School officials and health advocates fighting against the childhood obesity epidemic in the United States face an uphill battle when low-fat foods are among the higher-priced menu items, The Washington Post said Monday.

School systems across the United States operate much the same way as restaurants. With rising costs in labor and health food options, the price increase could be transferred to families already struggling to make ends meet.

The U.S. Agriculture Department raised its contributions to schools to provide free lunch to poorer families by 3 percent last year, but the cost of milk, for example, rose during that same period by 17 percent, the Post said.

Meanwhile, the operating budgets for school lunch programs suffer because the national economic outlook means lower state and local tax revenues.

School lunch coordinators take measures to keep lunch menus healthy, such as offering oranges instead of more expensive grapes.

"We're having to be creative," said one school chef, "but we're worried it's not sustainable."