Girls as young as nine are resorting to dieting after being teased about their weight, say British researchers.
About 20% of children have been teased about being fat
One in five nine-year-old girls and nearly as many boys have been bullied by classmates for being fat, a study has found.
Experts are concerned the taunts are contributing to the slimming fad among children, particularly young girls.
One in five girls are dieting by the age of nine, putting them at higher risk of developing an eating disorder in later life.
Dr Andrew Hill of the University of Leeds who led the research team said playground teasing was a strong currency.
"It's about growing up in a weight conscious society", he told BBC News Online.
Pressure from the media, peers and parents gives "the message that it is aesthetically pleasing to be slim".
Girls on diets tended to cut out meals, such as breakfast, avoid certain foods and eat fewer snacks and smaller portions.
Those who were being bullied were "more distressed psychologically" with lower self-esteem even though some were not overweight.
Young boys were also teased about their weight but were more likely to turn to exercise rather than slimming.
"It concerns me that we've got a particularly young age group who we are finding are embarking on a career of weight and shape concern," Dr Hill said.
"That is going to persist into adolescence, and become a risk factor for eating disorders."
The study was to be presented at the sixth London Eating Disorders Conference on Tuesday.