Many girls who did not see themselves as overweight were trying to lose weight anyway, the study found.
Of the 945 girls, 76 assessed themselves as underweight, 648 said they were normal and 221 said they were overweight.
"In our sample, 23 per cent of girls considered themselves overweight, whereas around 46 per cent are trying to lose weight," the study said.
The "relatively high degree of weight misclassification" was of concern.
Girls who incorrectly perceived themselves to be overweight might face a higher risk of eating disorders, the study said. "Conversely, overweight girls who are unable to recognise their condition are unlikely to initiate the lifestyle changes required to obtain a healthy body weight."
While both situations were bad, underestimating "excessive body fat" was a greater public health risk. Interventions and educational campaigns to help girls recognise a state of excess body fat should be a priority, the study said.
When it comes to body shape surely there is no normal? The choice of Stuff to focus it's coverage on the overweight end is predictable.