"One of the interesting findings of this study is that it applies to normal-weight kids also," said psychology professor and lead author Chad Jensen.
Researchers gave three surveys to 108 fourth- and fifth-grade students at six different elementary schools in the Midwest. One questionnaire assessed their well-being, including emotional health, relationships with classmates and academics.
Another asked about teasing, such as whether they were chosen for a sports team last or called insulting names while playing. The third zeroed in on how bullying affected them.
Kids also reported how often they did 21 kinds of physical activity, and researchers followed up with the same questions a year later.
They found the healthy-weight kids who were teased reported fewer minutes per day spent on physical activity, compared to the kids who weren't victimized. The overweight kids, meanwhile, reported negative physical, social, academic and emotional effects.
The results don't rule out other factors, but do show gym-class teasing is damaging, Jensen said.
"This doesn't allow us to say [that] we know this is why physical activity is reduced, but it seems to be a contributor," he said.
Gym class and recess could be a particularly vulnerable time for teasing because kids often have less direct adult supervision, he said. But with childhood obesity a growing problem in America, how can teachers and parents help keep kids active?
Anti-bullying programs can be effective, especially if adults know to keep a close eye on kids during P.E., he said. Parents can also talk to their kids about whether they've been teased and help them develop coping mechanisms, Jensen said.
"There's some skills we can teach kids to do if parents are aware this is happening," he said. "We just recommend we attend to the potential health outcomes of teasing."