By Farah Master

LONDON (Reuters) - Psychiatrists called on the government on Friday 18 September to address the soaring numbers of websites which promote anorexia and bulimia as a lifestyle choice rather than an eating disorder.

Encouraged by social networking sites like Facebook and "thinspiration" websites, growing numbers of Britons are looking online to get tips on how to starve or hide extreme weight loss, says the Royal College of Psychiatrists.

The appeal coincides with the start of London Fashion Week, whose organisers have refused to rule out using ultra-thin models on the catwalk.

"(These) websites normalise illness. In much the same way, the catwalks of international fashion events such as London Fashion Week can act as a showcase for underweight women," said Professor Ulrike Schmidt, chair of the college's eating disorders section.

More than 1.6 million people in Britain suffer from eating disorders, nearly 90 percent of them teenage girls.

The report calls on the government to tackle the proliferation of pro-eating disorder sites as part of its wider efforts to safeguard children on the internet through the UK Council for Child Internet Safety (UKCCIS)

Psychiatrists say 1 in 10 girls look at pro-eating disorder websites repeatedly, taking inspiration from celebrities like Lindsay Lohan and Paris Hilton. Some websites use photographs of excessively thin models and messaging forums to encourage severe weight loss.

Beat, a charity for people with eating disorders, said steps to make the sites illegal would not solve the root problem.

"Directing people away from these sites, towards pro recovery sites is what we would wish to see," said its spokeswoman Mary George.

Beat said it is already working with the AOL internet service provider to filter searches.

"If somebody puts in a search for pro anorexia websites, our website comes up first," said George.

The UKCCIS said it was working hard to ensure that vulnerable young people are signposted towards places where they can get help when accessing such sites.

(Editing by Steve Addison)