KANSAS CITY, Mo. – School nutritionist Leah Schmidt has always loved trying to serve healthy meals that nose-wrinkling children will actually eat.

The challenge may soon become too hard, Schmidt fears. The School Nutrition Association is calling on Congress and the U.S. Department of Agriculture to ease up on the next round of federal healthy food requirements, which are due July 1.

Schmidt, who works in the Hickman Mills district in Kansas City, is the current national president of the nutrition association.

The nutritionists are worried about three regulations. One would require all grain servings to be rich in whole grains — or more than 50 percent whole-grain — affecting pastas, bread, rolls and pizza crusts. The current rule requires half the grain servings to be rich in whole grains.

Another rule would require children to pick up a fruit or vegetable with each meal, rather than expecting servers to encourage it. Schools fear it will lead to food waste.

The USDA also is phasing in steep limits on allowable amounts of sodium, which would become a problem with the levels expected by 2017, Schmidt said.

"One deli turkey sandwich with cheese and mustard would use up most of the sodium for the week," she said.

Schools are already feeling some strain, the nutrition association said. Since the new standards were first implemented in 2012, the number of children participating in lunch and breakfast programs has fallen by 1.2 million, from 31 million to less than 30 million.

Schools have already responded to weekly limits on calories, sodium and fat while meeting rising expectations on nutrients, grains and meats — all variable according to the ages of students.

The calories within the overall limit can't be more than 30 percent fat.

The USDA acknowledges that schools have come a long way toward providing healthy meals. More than 90 percent are meeting the standards.

Janey Thornton, a USDA undersecretary, acknowledged the food industry isn't ready to meet the coming sodium standard, but she encouraged school lunch directors to "worry about today first before we imagine the worst down the road."

Thornton said problems will lessen as the food industry creates healthier products. "I'll bet that five or seven years down the road, we'll see kids eating healthy food and we'll see acceptance," she said.