Researchers at the New Flinders University interviewed more than 1000 high school girls and found conversations about appearance were intensified on social media, and were more influential because they involved peers.

The girls who were first interviewed aged 8 and 9 years were asked about their social media habits and self-esteem. They were then interviewed at the ages 10 and 11. By then 90 percent had a Facebook account, with an average of 475 friends and were uploading pictures of themselves to the internet, a daily reported.

The time the girls spent on social media had blown out from one hour 45 minutes a day to two-and-a-half hours. Although 80 percent of the girls surveyed were classified as normal weight, 46 percent said they were dissatisfied with how much they weighed.

"Time spent on social network sites was related to lower self-esteem, body-esteem, sense of identity and higher depression," researcher Amy Slater said. Young girls seeking affirmation via social media were "setting themselves up for negative mental health outcomes", social commentator Melinda Tankard Reist said.

"They feel they have to be on display. We live in a culture that rewards exhibitionism (and) everyone is judged on their physical appearance," Reist said. Experts believe social media has a more powerful influence on teenage girls than traditional media because it is so pervasive and interactive.

(Agencies)