A new research conducted by the Westmead Millennium Institute in Sydney have found that contrary to long -perceptions on vanity, it is the obese boys who are more stressed over their body image than their equally overweight girl counterparts.

In a study that started off in 2004-05 which involved more than 2,000 Australian schoolchildren who were about 12 years old at the time, researchers were surprised to find out that the negative psycho-social impacts of obesity were "greater on teenage boys than upon teenage girls."

"Girls in this study who were either overweight or obese did not have significantly different quality of life scores compared to normal-weight girls," Dr Bamini Gopinath, lead author of the study, said.

The researchers used a questionnaire to assess whether being overweight or obese influenced the kids' quality of life when they went back to follow-up five years after. The respondents were now aged around 17 or 18 at this time.

The boys in the survey gave random explanations, but researchers believed the reason for the poor self-image as well as the stress could be related to the importance of sport to boys.

"If obesity is limiting their participation in sport, it might negatively affect their social functioning and/or physical functioning, both of which are measured as part of the total score," Dr Gopinath said.

"Particularly with the Australian culture, the participation in sports for boys is quite an important aspect," she added to ABC.

"So it could be that the overweight or obese boys tended to not participate so much in sporting activities and therefore this could have an adverse impact on their body image, self-esteem."