More than 2000 British children were treated for eating disorders over the past three years, newly released figures show.
It has also been revealed that just under 600 were aged 12 or under, 98 were aged between five and seven, 99 aged eight or nine and almost 400 between 10 and 12.
The figures came from 35 national health service trusts in England, Sky News reports.
About 2100 children under 16 were treated over a three-year period.
Francis Burrows from eating disorder charity B-eat said it was a "sad statistic", but that it only represented those people being treated in hospital.
The figures, released under the Freedom of Information Act, are believed to be an underestimate, according to reports.
Some hospitals treating these patients refused to provide any data, the Guardian reports, while others would only release figures for children admitted after becoming dangerously thin, excluding those undergoing psychiatric therapy as outpatients.
About three in every 100,000 children under 13 in the UK and Ireland have some sort of eating disorder, according to a study conducted by experts from University College London's Institute for Child Health.
A study published by the Royal College of Psychiatrists in April said that "urgent action" was needed to improve the detection of eating disorders in young children, as well as the services available to help them, Sky News reports.
The study showed that over a 14-month period, 208 cases of early-onset eating disorders were confirmed in children aged between five and 13 in the UK and Ireland.
Most of the children were girls - with boys accounting for 18% of the total.
Dr Dasha Nicholls, lead researcher for the study, said that services might have to adapt to deal with the issue.
"Many eating disorder services are aimed specifically at adolescents. Childhood eating disorders are not quick or easy to treat," she said.
"For a minority of children it may be the start of a severe and enduring illness, with death rates comparable to some forms of leukaemia.
"Our study shows there is an urgent need to consider the needs of children with eating disorders separately - and not simply lower the age range of existing adolescent services."
Other research published in the British Journal of Psychiatry earlier this year suggests one in five children diagnosed with an eating disorder have a history of early feeding problems, such as fussy eating, the Telegraph reports.
Almost half of those diagnosed with disorders by the age of 12 had a close family member with a mental health problem such as anxiety or depression, it says.