Sick support: how websites encourage bulimia, anorexia's ugly sister.

Discontent is pathoplastic - that is, it changes shape in response to the sometimes silent, sometimes violent shifts we call socio-cultural change. Once upon a time, women would lament their lack of curves, and then they became aggrieved by the faintest trace of adiposity - meet Sara. At least once a week, Sara ventures to a mall on the very outskirts of her city. This distant destination, Sara hopes, will minimise the likelihood of her being recognised. Her's is a stealth born of shame and compulsion; a silent, unaccompanied foray to an out-of-the-way mall, driven in equal parts by desire and despair. Inside the mall, Sara heads for the unhelpfully large hypermarket. Within its stadium-sized snack-food section, she selects her favourite chocolates, cakes, and crisps, along with a very brightly coloured fruit juice.

Back in her room, she consumes the 6,000-calorie snack with the inelegant determination of a pie-eating contestant. The rapidity of consumption is in no way an indicator of gastronomic delight; this is more self-harm, than self-indulgence. Sara is careful to initiate her feeding-frenzy with the fruit juice - juice first, cake last, her mealtime-mantra. With the last of the cake devoured, and feeling uncomfortably full, the ritual makes its way to the bathroom. Head over the toilet bowl, Sara regurgitates her binge, not content to cease vomiting until she spots the reassuring orange of the fruit juice contrasted against utilitarian white of the toilet - first in, last out, she reasons.

Welcome to the world of disordered eating. The scenario illustrated above is bulimia nervosa, sometimes rather hurtfully referred to as anorexia's ugly sister. Anorexia and bulimia can cause immense physical and psychological distress to those experiencing them. Furthermore, the distress experienced by families, friends and loved ones is, for most of us, unthinkable. Imagine impotently watching your 17 year-old daughter slowly starve herself to death. Ninety-five per cent of anorexia sufferers are female, and mortality rates are estimated at between 10 and 20 per cent.

Despite the distress, dysfunction and life threatening complications associated with anorexia and bulimia, there are some who have advocated the idea that eating disordered practices are a lifestyle choice. The ill thought-out arguments behind such claims typically cite the Roman custom of visiting the vomitorium after feasting as an example of some kind of "functional bulimia". However bulimia is highly ego-dystonic, that is, bulimic behaviours make the individual feel guilty, sad, and ashamed - hardly the type of behaviour you would associate with celebratory feasting. Furthermore the behaviours tend to be solitary, secretive, and are experienced as a compulsion, rather than a choice.

While these unhealthy ideas about eating disorders as a lifestyle choice were once confined to fringe publications, and given very little attention at all, the internet has remedied that. In recent years, we have witnessed the emergence, and proliferation of the pro-anorexia website. These "pro-ana" sites, as they are known, are typically run by sufferers of eating disorders and offer site visitors "thinspiration" in the form of before and after pictures promoting dangerously low body weight as a beauty ideal, along with dangerous advice about fasting, excessive-exercise, and other extreme weight-loss measures.

Johns Hopkins Bloomberg School of Public Health and the Stanford University School of Medicine have recently undertaken the first large-scale analysis of these pro-eating disorders websites. The study, published this month in the American Journal of Public Health suggests that such sites exist on a continuum, from the fairly banal to the outright dangerous. At the more dangerous end of the spectrum, site content informs and motivates eating disordered behaviours and the attainment of dangerously low bodyweights.

I decided to have a look at a few of these sites for myself, having had a professional interest in eating disorders for a number of years. One of the sites I reviewed was called "Pretty thin" a site that claims to be a place for the "beautifully thin" and "a location for those choosing to take the ana lifestyle upon themselves". The ana lifestyle? The site, at times, has an almost religious undertone, with the webmaster dedicating the site to "those of us who ana has already found". Anorexia nervosa, a mental illness given its name by Sir William Gull (a lead suspect in the Jack the Ripper murders) has been anthropomorphised into "Ana", a benevolent quasi-deity who confers the gift of extreme thinness on her chosen devotees.

The media has often been blamed for the proliferation of eating disorders. Pressure groups, like the Eating Disorders Association, have campaigned, often very successfully, to bring about reform. However the internet has given rise to a fragmentation of the media, which some predict will only intensify. We need to consider new ways of responding to the potentially health-damaging messages that are available via the internet; let's call it public health in cyberspace or online-community health.

A vital first step is to be aware of the potentially harmful information that is getting a lot of attention - site statistics can help to quantify this. Such surveillance data could potentially inform priorities, policies and campaign content. Justin Thomas is professor of psychology in the department of health science at Zayed University in Abu Dhabi