By Stephanie Stahl

PHILADELPHIA (CBS) — A new study says students aren’t getting enough time to eat lunch. The research suggests that when kids are pressed for time they could be losing out on important nutrition.

School lunches aren’t about the food for most kids.

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“When I get to sit down and eat and be free to talk with my friends,” Woodland Elementary School fourth-grader Hailee Leroy said of her favorite part of lunch.

New research shows many students don’t get enough time to eat.

The Harvard University study looked at more than 1,000 students. Most had lunch periods ranging from 20 to 30 minutes.

But that’s not how much time the kids actually had to sit and eat.

“Because they didn’t have enough time to eat, they were throwing away on average between 10% to 13% of their meal,” Harvard University Assistant Professor of Nutrition Juliana Cohen said.

Researchers expected to find kids just throwing away their vegetables when pressed for time.

But that’s not what happened.

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The study found that students who have less than 20 minutes to eat their lunch ate 13% less of their entrees, 12% of their vegetables and 10% less of their milk compared with classmates who had a minimum of 25 minutes to eat lunch.

It can be even worse depending on when you get to the cafeteria.

“If you’re at the end of the food line, it can be as little as 12 minutes to eat,” school health pediatrician Dr. Robert Murray said.

The Hunger Free Americans Act mandates healthy school lunches, but there’s no federal standard for how long lunch periods should be. That’s left up to school districts to decide.

Experts say the ideal time is 30 minutes with 25 minutes seated. Most schools in the Philadelphia region allot 30 minutes for lunch.

Experts say giving kids time to eat shows up in their academic results.

“So things like impulse control, working memory, all the types of behaviors that you want in a classroom that enables students to learn,” Cohen said.

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Time to eat is especially important for low-income students who get free lunches that account for much of their daily nutrition.

Stephanie Stahl