School cafeterias will be serving more-nutritious meals with twice as many fruits and vegetables, more whole grains and less sodium and fat under new guidelines that will revamp the federally backed school meals program for the first time in 15 years.

The meals will continue to include pizza and french fries because Congress, after heavy lobbying from the food industry, derailed the Obama administration’s original plan to limit tomato paste and starchy vegetables such as potatoes.

Even so, consumer groups hailed the changes as a major improvement over the current standards, echoing remarks by first lady Michelle Obama when she unveiled the new nutrition rules Wednesday at Parklawn Elementary School in the Alexandria section of Fairfax County.

“When we send our kids to school, we expect that they won’t be eating the kind of fatty, salty, sugary foods that we try to keep them from eating at home,” said Obama, who has championed efforts to combat childhood obesity.

Under the guidelines, which cover breakfast and lunch, schools that participate in the federal program must offer a mix of fruits and vegetables daily and offer double as much as currently required. In return, the schools get a federal subsidy on the cost of the food.

Schools also must offer only fat-free and low-fat milk, limit calories based on the age group served, gradually lower the amount of sodium in meals, and stop serving foods or ingredients that have trans fat.

As the Agriculture Department was crafting the final guidelines, opponents raised concerns about the program’s estimated $6.8 billion price tag over the next five years and the financial burdens it would place on school districts.

In response, the administration slashed the cost to $3.2 billion. It did so by abandoning plans to have schools offer meat or meat alternatives for breakfast. The administration also decided to phase in the standards over three years for the breakfast program, which should reap additional savings. The rules will kick in for school lunches next school year.

The program’s costs also will be offset by a number of revenue-raising measures, USDA officials said. For instance, schools that meet the new standards will get an additional 6-cent increase in lunch reimbursements — the first increase in 30 years.

“The only disappointment is that Congress did not allow USDA to limit french fries and that they were forced to continue to count pizza as a vegetable,” said Margo Wootan, director of nutrition policy at the Center for Science in the Public Interest. “But at least that pizza will be lower in sodium and have a whole grain crust and be served with an additional vegetable on the side.”

The USDA had initially proposed a one-cup-per-week limit on the amount of white potatoes and other starchy vegetables served to schoolchildren.

The proposal also would have nixed the favorable treatment of tomato paste. Currently, one-eighth of a cup of tomato paste is credited with as much nutritional value as a half-cup of vegetables and thus counts as one vegetable serving. In effect, that enables food makers to market a slice of pizza as a vegetable. The USDA wanted to bring tomato paste in line with the standards granted to fruit pastes and purees, such as applesauce.

With a strong push from potato growers and some food manufacturers, a group of Senate and House lawmakers agreed to scrap the USDA’s tomato and potato proposal when negotiating an agriculture spending bill.

But Kevin Concannon, a USDA official, said he’s not concerned that these elements are missing from the final package. “What is really important is that for the first time we’re recommending minimum amounts of all the food groups,” said Concannon, USDA’s undersecretary for food, nutrition and consumer services.