A new study shows just how much sugary energy drinks affect kids.

The Yale School of Public Health did a study on obesity and unhealthy hyperactivity in twelve year-olds. The researchers say the more energy drinks the kids drank, the more the kids were hyper and couldn’t focus. Researchers say just one of these drinks can contain more sugar than what a child should consume in an entire day. Currently, about one-third of American school children are considered overweight or obese.