The number of schoolchildren participating in the school lunch program continues to decline, as 1.4 million students have dropped out of the program since First Lady Michelle Obama’s lunch rules went into effect.

A new Government Accountability Office (GAO) report found that schools are still struggling to meet the healthy rules, with kids not taking to sweet potato tater tots or whole grain pasta.

"Nationwide, participation in the National School Lunch Program has declined in recent years after having increased steadily for more than a decade," the GAO said in its report released Wednesday. The government watchdog found that 1.4 million students have stopped participating in the program since the 2010-2011 school year, a 4.5 percent decline. In 2014, 30.4 million students participated, down to 2006 levels.

The GAO interviewed eight state child nutrition directors, and visited eight school food authorities (SFA) for its analysis of the program, finding that the Healthy Hunger-Free Kids Act, championed by Mrs. Obama, is to blame for smaller lunch lines.

"Officials from seven of the eight states we interviewed in school year 2014-2015 reported that the decreases in lunch participation were influenced by student acceptance of the changes made to comply with the new lunch content and nutrition standards," the GAO said.

The report noted that many schools are still struggling with plate waste, as five of the eight SFAs reported problems. However, the GAO said its "lunch observations suggest that plate waste may be beginning to decrease as students adjust to school meals that meet the new requirements."

Another "longstanding challenge" is getting kids to like the food served, especially whole grains.

"Representatives from five of these SFAs highlighted whole grain pasta as being particularly challenging to serve, with one noting, for example, that whole grain-rich pasta loses structural integrity soon after being served, becoming unappealing to students," the GAO said.

When the standards took effect in 2012, only half of grain products had to be whole grain-rich. This past year all white grains were eliminated and cafeterias can only serve whole grains.

The GAO said that schools could apply for a "temporary pasta exemption" from the federal government if they want to serve regular pasta noodles.

The lunch rules have led to some schools to serve sweet potato tater tots, which kids "have not embraced." Others have dropped certain cereals, biscuits and gravy, and chili from their menus to meet the sodium guidelines.

Last year was the first time schools had to lower sodium levels below 1,420 milligrams for high school, 1,360 milligrams for middle school, and 1,230 milligrams for elementary students. By 2022, the lunch law requires schools to cut those levels in half.

The first target has already caused some school districts to replace all added salt with pepper, which "resulted in a strong pepper flavor for many foods." Others had to remove pickles from condiment stations.

The GAO also reported that children are bringing salt and pepper shakers to class, similar to other reports that kids are creating their own black markets for salt and sugar as a result of the rules.

"SFA directors, state officials, and industry representatives we interviewed expressed concerns about the future sodium targets for school meals," the GAO said. "Directors and staff from three SFAs indicated that they made changes to food that are within their control in order to meet the first sodium requirements, and those from two noted that they are doubtful it will be feasible to meet the future targets without changes made by the food industry."

The U.S. Department of Agriculture (USDA), which administers the school lunch and breakfast programs, said it is not making any decision about future sodium requirements until the Dietary Guidelines for Americans are released later this year.

The GAO also found that students still do not like peas.

"In our June 2013 testimony, we also found poor student acceptance of vegetables in the beans and peas (legumes) and red/orange vegetable subgroups, and we found during our recent SFA visits that this challenge has persisted for five of the eight SFAs," they said.

Half of the school districts interviewed by the GAO reported increased food costs due to the healthy rules, and two said they incurred a net financial loss.

USDA officials said they "generally agreed" with the GAO’s findings.

"The officials said that they intend to continue providing menu planning guidance and technical assistance to states and districts to help them comply with these requirements," the GAO said.