WASHINGTON — Eating healthy food isn’t always cheap, and some conservatives in Congress are concerned that the Obama administration’s effort to make school lunches more nutritious is a luxury the nation can’t afford.

Many schools, especially the poorest ones, agree. They say new rules issued by the Agriculture Department in January will require them to buy pricier foods and more equipment at a time when federal and state budgets are tight and food costs are rising.

The new menus will cost an additional 14 cents a meal, according to the Agriculture Department. A spending bill approved Tuesday in the House Appropriations Committee estimates that the new lunch rules could cost schools an additional $7 billion over five years. Saying that “unrealistic demands” can lead to burdensome costs, the Republican bill directs USDA to rewrite the rules so they wouldn’t force schools to spend additional money.

“I think what is unanswered is where will the resources come from,” says Lucy Gettman of the National School Boards Association, which has said the bill puts too many unfunded mandates on schools.

Under the USDA rules, schools would have to cut sodium in subsidized meals for low-income children by more than half, use more whole grains and serve low-fat milk. They also would limit kids to only one cup of starchy vegetables a week, so schools couldn’t offer french fries every day.

Potatoes are cheap and schools said that replacing them in the menus would increase costs. More expensive whole grains would be incrementally increased to the point that most grains in lunches are whole.

Schools also have expressed concern about requirements to serve more dark-green vegetables. According to Diane Pratt-Heavner of the School Nutrition Association, which represents school lunch workers, many schools have struggled to get kids to try spinach, collard greens and turnip greens and have had more luck with broccoli and lettuce. But some lettuce prices spiked earlier this year because of harsh winter weather.

Equipment is also a major cost, and the School Nutrition Association has expressed concern that additional coolers and freezers would be required to store the larger amount of fruits, vegetables and proteins required by the rules.

Some of these costs will be defrayed through a 6 cent-per-meal reimbursement included in a child nutrition bill signed by President Barack Obama earlier this year, along with a provision in that legislation requiring schools to increase the cost of paid meals to make up for some of the higher costs. But some schools say it won’t be enough.

Sally Spero, food planning supervisor for the San Diego unified school district, said the changes to school breakfast programs — they call for more proteins and fruits and vegetables — will cost her district $4 million.

“We’re being asked to serve a much bigger meal than my colleagues and I think that the kids can even eat,” Spero said. “Nothing is more upsetting than to see that food go into the trash.”

She said the changes could mean that school districts may have to skimp in different ways, like serving more canned fruits instead of fresh fruits, despite government efforts to promote the opposite.

“I just feel like there are a lot of unintended consequences,” Spero said.

Advocates say that many schools are already following the new rules and that changes may be more expensive now but will defray health costs in the long term. The government spends billions of dollars a year on obesity-related diseases like diabetes. First lady Michelle Obama has made the healthier lunches a major part of her “Let’s Move” campaign to combat the growing childhood obesity problem.

“People think because they aren’t paying for it now they can save money, but we are paying for it now,” said Margo Wootan, the director of nutrition policy at the advocacy group Center for Science in the Public Interest.

Associated Press writer Christine Armario in Miami contributed to this report.