Girls as young as six say they are unhappy with their bodies and want to be thinner, a study has suggested.
A team from the Flinders University of South Australia interviewed over 80 girls aged five to eight.
The British Journal of Developmental Psychology study found 47% wanted to be slimmer, and most thought that would make them more popular.
The UK Eating Disorder Association said it was known that children as young as eight had been diagnosed with anorexia.
Because of the girls' age, the researchers asked them about their awareness, rather than actual experience, of teasing and likeability on the basis of body shape.
They were also asked what they thought about their peers' level of body dissatisfaction, and how much body shape was discussed accepted amongst the girls they knew.
Researchers also questioned the children on how much they knew about dieting.
Forty-five per cent said they would diet if they gained weight, with older girls in the group more likely to do so.
Most girls believed being thin would increase likeability, yet very few claimed to discuss their bodies with their friends.
Five-year old girls displayed little dissatisfaction with their bodies.
Peer influence 'key'
Researcher Hayley Dohnt, who led the study, said: "Previously, research has focused on adolescence as the likely time for the emergence of body dissatisfaction.
"However, clear evidence has accumulated that a substantial number of pre-adolescent girls are dissatisfied with their bodies and wish to be thinner."
She added: "Previous research has also focused on parental influence as the most salient source of information for young children.
"However, the major life event which occurs over the five - seven year age range, when body dissatisfaction begins, is the commencement of schooling.
"Therefore, peer influence, which has been investigated extensively for adolescents but has been assumed as more or less irrelevant for young children, may in fact be particularly salient for this age group".
A spokesman for the UK's Eating Disorders Association said: "Eating disorders have been recorded in children as young as eight, and there may have been instances in children of an even younger age.
"Low self esteem is a major contributory factor of eating disorders: media images, peer pressure and family situations can also affect people.
"We believe there are lots of pressures from many areas on young people to be thin. We are concerned but not surprised that school children as young as six are affected by them."
He said the EDA already carries out work in schools aimed at addressing self esteem and negative body image issues.
But he added: "The fact remains that the key age for developing eating disorders is 13-15."