On a Wednesday afternoon, the yellow and green cafeteria at P.S. 161 was full of students talking and shouting. One sat down and pulled out a Lunchables, a prepackaged meal combination, but everyone else headed straight for the school kitchen. Most eagerly ate their sweet and sour roasted chicken, but didn’t touch the rice or collards with sweet tomato on their white Styrofoam trays.

Sometimes the school lunch is tasty, but “sometimes it’s disgusting,” said one fifth-grader, poking at her collards with a plastic utensil called a spork. “The vegetables are nasty.”

Her classmate agreed. “I like vegetables at home,” he said, but at school they just don’t taste good.

For some children, whatever they think of school food, there aren’t many alternatives. In low-income neighborhoods, many students get free or reduced-price lunches at school, which become a primary source of nutrition for the day. At this school, 93 percent of the student body lives at or below the poverty level and can be eligible for free or reduced-priced meals.

But critics charge that the meals aren’t always that nutritious or tasty and contribute to larger health problems. Financial and logistical problems make it difficult for the Office of SchoolFood to improve the cuisine, and despites its efforts, change can be slow in coming, the advocates say.

Some students eat little of what the school gives them, said Nayvi Merino, whose son is a first grader at P.S. 161. Merino works as a restaurant hostess in midtown, and although she gets home as early as she can in the afternoon, she said, often her son is ravenous.

“It worries me,” Merino said. “He’s not eating well at school.”

For students who do eat their fill, school food advocates have cited unhealthy lunches as a contributing factor to New York’s childhood obesity rate. Forty-three percent of the city’s children are overweight and about half of those are obese, according to a 2004 study conducted by the New York City Department of Health and Mental Hygiene. Many of these children come from low-income communities.

School lunch programs are “horribly underfunded,” said James Subudhi of WE ACT for Environmental Justice, so schools are often forced to take short cuts to meet federal nutrition requirements, which limit fat content and mandate that school meals provide at least a third of the recommended daily allowances of protein, iron, calcium and Vitamins A and C.

The Office of SchoolFood’s budget allows about 90 cents per meal, limiting the amount of fresh ingredients it can buy, said Nancy Easton, co-founder of Wellness in the Schools, a grassroots organization that works to improve nutrition, health and fitness in public schools. A typical menu item is a “golden fish and cheese sandwich,” which Easton described as “mystery meat fish with mystery cheese on top wrapped in a breaded substance that has been frozen for a long time.”

By contrast, Harlem Children’s Zone schools, part of a nonprofit organization aimed at helping disadvantage families break the poverty cycle, spend about $6 on each meal, which normally contains organic vegetables and meat, Subudhi said.

But school food issues aren’t only budgetary; they’re also logistical. The Office of SchoolFood is charged with feeding about 860,000 students a day, Marge Feinberg, a Department of Education representative, said in an email.

At overcrowded schools where cafeteria time is precious, some students eat lunch at 10:30 a.m., Subudhi said. Many kitchens don’t have the necessary appliances to cook from scratch, forcing them to serve only reheated food, Merino added.

And almost all the kitchen staff lack formal culinary training, Easton said. When it comes to schools preparing nutritious, high-quality food, “all the odds are against them,” she said.

The Department of Education declined to comment on these obstacles.

Some problems are simply beyond the Office of SchoolFood’s control. Several students at P.S. 161 said they just didn’t like eating vegetables anywhere. But pizza, served every Friday, got rave reviews from nearly everyone.

And some students, like P.S. 161 fifth-grader Aaron Valdidia, don’t have problems with school meals. “I think they’re pretty good,” he said.

In the past five years, the Department of Education has taken steps like eliminating trans fats, replacing white bread with whole wheat and including more locally grown vegetables in its food, Feinberg said.

It has also put a salad bar in every high school, something Daniel James, an 18-year-old at Alfred E. Smith High School praised as “going the right way,” even though he usually skips the cafeteria lunch and grabs Subway after school.

But Merino would like to see a salad bar in every school, not just high schools. “Some of the stuff we want,” she said, “it’s not really that hard.”