A new study by Queen's University researchers should just about banish the stereotype of the jolly fat girl once and for all.
The study published in the European Journal of Obesity found obese girls were three times more likely to be bullies than their normal-weight peers.
The study points to the deep psychological wounds obesity inflicts, especially how it perpetuates itself.
Researchers studied 1,738 Ontario high school students over a two-year period, interviewing them in 2006 and again in 2007. Teens were asked questions about bullying and provided their height and weight so researchers could calculate their body-mass index.
Obese girls were 1.32 times more likely to be physically bullied than their slimmer classmates and 1.52 times more likely to be the physical bully. But when it came to non-physical types of bullying, such as teasing, taunting, shunning or spreading rumours, obese girls were three times more likely to indulge in this sort of relational bullying.
"We suspect that it might have something to do with them being treated that way by other people," study co-author Atif Kukaswadia told the National Post. "They internalize that and project it back outwards. But we don't really know, we would have to do a lot more research to figure out what exactly is going on."
Psychology professor Wendy Craig, another of the study's authors, said it shows the cyclic nature of bullying, how being bullied can turn obese people into bullies.
"Likely it is a cycle where they take out on others their anger and hostility at being victimized themselves," said Craig, an expert on bullying.
"Obese kids do tend to be picked on," Kukaswadia, a doctoral student with the Queens department of community health and epidemiology, told CTV News.
"When we found that they were also perpetrating the behaviour, that is concerning that they are involved in the behaviour as a victim and as a perpetrator."
The study found obese teenage boys often were also trapped by the bullying cycle. They were 1.71 times more likely to be physical bullies and 2.11 times more likely to be victims of relational bullying, though they were not more likely to practise it themselves.
The researchers acknowledged the study involved only a small group of students and offers nothing definitive on why obese kids perpetuate the cycle of bullying.
They say evidence suggests anti-bullying programs have some effect in decreasing the behaviour.