It started, like so many issues in newspapers, with an apparently casual remark: 'Our culture is obsessed by The Thin, by the obesity versus anorexia debate, by our constant taboo pursuit of thinness.'

Polly Vernon's Fashion Plate column in Observer Food Monthly, headlined 'Admit it. You hate me because I'm thin', described how she lost two stone in six months, dropping from 'size 10 going on 12, to a size six, going on eight'. Consequently, she was embraced by 'a fast and glam super-thin super-class' and was summoned for inspection by her former colleagues on Vogue 'where thinliness is not just next to godliness, it rates way, way above it... Contrary to popular belief, being thin has made me happy,' she wrote. 'I've spent probably 16 years wondering if I would look better if I were skinnier, and now I know for sure. I do.'

Readers were further provoked when OM ran a series of pictures of waif-like models. One letter, signed by five women, said: 'The fashion industry, and by extension yourselves, portray these women as the ideal of beauty, when in fact they look as if they have been starved. The message that this sends - that we women should aspire to look like this, with our ribs sticking out - is both deplorable and irresponsible.'

But can pictures of super-waif models and columns such as Fashion Plate, actually encourage young women to lose weight to alarming levels?

Only 7 per cent of those polled by our Body Uncovered special supplement last month felt the media could not be held responsible for dictating the public perception of ideal body shape.

One family was particularly angered by the piece. They have a daughter who is currently receiving treatment for anorexia nervosa, and interpreted that 'obesity versus anorexia' comment as a suggestion that anorexia is somehow a lifestyle choice. 'You don't choose anorexia; it chooses you,' they wrote, adding a distressing description of their daughter's time in hospital.

Anorexia nervosa has the highest mortality rate of any psychiatric condition - the Eating Disorders Association estimates that 18 per cent of sufferers will not survive. They are usually highly intelligent, gifted young females aged between 15 and 25, but with a perfectionist disposition that drives them to starve themselves.

Steve Bloomfield for the association said: 'There is a danger that the media can influence those who are feeling vulnerable. Young women in an emotional state may look at photographs of slim, glamorous, successful people and imagine that if they looked like them their problems would go away.'

When the Bread for Life Campaign surveyed 900 young women it found that more than 60 per cent felt inadequate compared to media images of beautiful women. Nearly 90 per cent thought more average-sized models should be pictured in magazines and 63 per cent wanted fewer features on dieting. That was five years ago, yet there is little sign of the media taking any notice.

Deanne Jade of the National Centre for Eating Disorders has attempted to establish to what extent the media might be held responsible for a supposed growth of eating disorders. 'There is no doubt that ideal body size, as reflected in style icons, is getting thinner,' she says, adding that the body size epitomised by Victoria Beckham or Calista Flockhart is unrealistically thin. At the same time the increasing availability of high-calorie foods means that people are actually getting bigger, so that the gap between actual body size and the cultural ideal is getting wider.

'There is a lot of dieting going on as a result, even if excess weight is all in the mind. Studies show that of all people who diet, half are not even overweight. However, dieting does not inevitably lead to anorexia, and anorexia is not a slimming disease.'

She warns: 'It is hard to separate the influence of the media in the development of eating disorders. Studies point to the correlation between low self-esteem and eating distress. The media may contribute to low self-esteem by promoting slenderness as the pathway to gaining love, acceptance and respect, while at the same time reflecting a trend in society to demonise fat.'

I put all this to Polly Vernon. She believes the tacit promotion of thinness in TV programmes such as Friends is arguably more dangerous than her acknowledgement that thinness is celebrated, whatever anyone says. 'Pop culture generally quietly champions it, or worse still, offers it up as the norm, yet simultaneously officially recognises that this shouldn't be the case. Isn't tackling it head on, with some honesty, more useful?' she asks.

Honesty, of course, but if we promote the notion that 'thinliness is not just next to godliness, it rates way, way above it' and run pictures of stick-thin models, we are doing just what the experts warn us against: we are influencing vulnerable young minds.

I asked several health organisations if they issued press guidelines on the proper use of labels such as 'anorexic' and 'bulimic'. While they offered useful definitions, none had easily available advice. The Independent Television Commission and the Advertising Standards Authority have rules to ensure advertising does not stimulate unhealthy attitudes to eating or imply that being underweight is desirable, but no clear guidelines exist. We shall shortly be framing some for inclusion in our new house style guide.

· Anorexia and Bulimia Care: 01462 423351
· Eating Disorders Association: 01603 619090
· International Eating Disorders Centre: 01296 330557
· National Centre for Eating Disorders: 01372 469493
· Write to Stephen Pritchard, Readers' Editor, The Observer, 119 Farringdon Road, London EC1R 3ER, tel 020 7713 4656 Mon-Fri, fax 020 7713 4279 or email readerl@observer.co.uk