Australian teenagers as young as 14 are taking extreme measures including vomiting or taking laxatives to control their weight.

A new government study found while a very small minority of mid-adolescents met the criteria for anorexia or bulimia, significant numbers had taken action to try and control their weight.

The Growing Up In Australia Longitudinal Study of Australian Children found girls were more worried about their weight than boys, and many consider their weight an important measure of how they felt about themselves.

Australian Institute of Family Studies Executive Manager Galina Daraganova said that along with expressing negative feelings about their weight, some teenagers also took quite serious actions to try and control it.

This included making themselves vomit, taking laxatives or appetite suppressants, skipping meals and exercising for the sole purpose of losing weight.

Dr Daraganova said that among the 14 and 15-year-olds who were dieting, about half of the boys and a third of the girls were actually overweight, according to their body mass index.

The study found girls who were dieting at age 14 and 15 had higher levels of emotional problems, compared to those who were not dieting.

"Among girls who were dieting at this age, 58 per cent had elevated depressive symptoms and 47 per cent had elevated anxiety symptoms," Dr Daraganova said.

"Among boys dieting at age 14 (and) 15, 31 per cent had symptoms of depression and 16 per cent had symptoms of anxiety, twice that of boys who were not dieting."

She said dieting did not impact physically on adolescents in the study, but had a marginal, negative effect on adolescents' levels of school and social functioning.