Researchers compared more than 750 school meals with more than 560 packed meals given to pre-K and kindergarten students in three schools, analyzing them for nutritional value over five days, CBS News reports.

“We found that packed lunches were of less nutritional quality than school lunches,” said lead researcher Alisha Farris, a Ph.D. candidate at Virginia Tech University.

The packed lunches had more fat, and included more desserts and sugary drinks than the school lunches did, the researchers found.

“There was a spectrum,” Farris said. “There were some really healthy packed lunches. But overall, they were pretty unhealthy.”

The study is published in the November-December issue of the Journal of Nutrition Education and Behavior.