Everyone knows that overweight kids have an elevated risk of all sorts of negative health outcomes: diabetes, heart disease, high blood pressure, depression, and more. But a fascinating new study just found that obese kids may also have academic problems—especially with math.

The study, published in the journal Child Development, found that kids who were “persistently obese”—meaning they were obese since at least kindergarten—had lower match scores than kids without weight issues. They also scored worse than kids who because obese later

Now we have to be careful—obesity itself is not the cause of poor math aptitude. The researchers believe (and this makes good sense) that it’s the social issues that go along with obesity that create the problems. For example, obese kids are more likely to be depressed and lonely than non-obese kids. Those who are depressed and lonely spend less time with their peers and that may interfered with their school performance. Obese kids also tend to be ridiculed, teased, shunned, and excluded by their schoolmates. That makes having normal friendships harder because they don’t have the opportunity to develop good social skills.

Or, it could be the other way ‘round, according to Sara Gable who is the study’s lead author: kids who have poor social skills might be passed over as playmates, which makes them more likely to be isolated and depressed, upping their risk of obesity.

“For school-age children, one’s social standing is quite meaningful for one’s school experience and engagement in the learning process,” said Dr. Gable. “It’s important for kids to feel liked and capable in social situations with their peers.”