NEW YORK (Reuters) — Young sufferers of anorexia and bulimia who try to hide their eating problems from their parents and doctors are turning to a growing number of Internet chat rooms dedicated to perpetuating their illness.A pilot study of US eating disorder patients aged between ten and 22 showed that up to a third learn new weight loss or purging methods from Web sites that promote eating disorders by enabling users to share tips, such as what drugs induce vomiting and what Internet sites sell them.

But the study — published in the American Academy of Pediatrics’ journal Pediatrics — found that eating disorder sufferers were also learning new high-risk ways to lose weight from each other on Web sites aimed at helping them recover. The survey by researchers from Stanford University School of Medicine and Lucile Packard Children’s Hospital at Stanford showed a third of patients also visited pro-recovery sites and half of them learned new weight loss and purging methods.

“Parents and physicians need to realise that the Internet is essentially an unmonitored media forum,” said Rebecka Peebles, Packard Children’s adolescent medicine and eating disorder specialist and an author of the study. “It’s just not possible to completely control the content of an interactive site,” she said.

A wave of pro-eating disorder sites showed up on the Internet between 2001 and 2003, prompting operators of several Internet hosts to try to remove such sites. But the study showed many pro-anorexia and bulimia sites remain accessible, with most patients finding them and pro-recovery sites through chance searches.

“I feel so sick eating as much as 800 calories,” a teenage girl, who called herself “berlinium,” wrote in a pro-anorexia chat room on Monday.