Anorexia can be a devastating disease, not just for the sufferer, but also for the family and friends who have to watch a loved one in pain. Caroline Virr investigates a parent's viewpoint

American wit Dorothy Parker once claimed: 'It's impossible to be too rich or too thin.' But the recent, shocking pictures of Allegra Versace looking painfully thin, with a disproportionately large head and bones protruding through her skin, were enough to blow that theory out of the water.

Rumours had been circulating for months that the 20-year-old daughter of Donatella and her ex-husband Paul Beck was not well, but last month Allegra's parents issued an official statement.

It read: 'Our daughter, Allegra, has been battling anorexia, a very serious disease, for many years. She is receiving the best medical care possible to help overcome this illness and is responding well. As parents, we are doing out best to protect our daughter.'

This last sentence alone was enough to express the desperation and pain that both Donatella and Paul are feeling, and they are not alone. In the same month, Olivia Newton-John also revealed that her daughter, Chloe, had battled the disease. 'Maybe sometimes parents don't want to notice what's going on,' she said. 'As a parent, you want to think everything's okay. But all the therapists in the world can't help if the parents aren't present, loving and proactive.'

What is evident from these few, carefully-chosen quotes is that the parents of anorexia sufferers are all united by one thing: guilt.

No doubt the same heart-breaking pain was felt by the parents of Luisel Ramos, the 22-year-old Uruguayan model who died at a fashion show in August last year after suffering a fatal heart attack thought to be the result of anorexia. And the family of Ana Carolina Reston Mar-can, the Brazilian catwalk queen who died only three months later in a Sao Paulo hospital.

Ever since thinness was held up as the ideal, anorexia has rarely been out of the news but what are the exact causes of this potentially fatal disease?

The illness stems from an obsessive fear of gaining weight; voluntary starvation, often aided by vomiting and diet medicine, which can continue for years, destroying the constitution and causing osteoporosis in up to 50 per cent of cases, as well as weakening of the heart, immune dysfunction and low levels of essential hormones.

About one in 100 female adolescents are affected, and in 10 per cent of cases, the victim dies. Instead of watching their daughters blossom into confident young women, many parents become 24-hour carers as their offspring starve themselves to death.

It is easy to blame the fashion industry, given the trend for size zero models and digitally-enhanced images of celebrities splashed across magazines and newspapers every day. But scientists are beginning to cite genetic factors and parents of sufferers need no encouragement to blame themselves.

Jo Kingsley, who watched her daughter Alice battle anorexia from the age of 14, says: 'It's a horrible, deceitful illness. As a parent, you feel guilty and ashamed. When she was 14 and eating crisps, we'd say, "Be careful, you'll put on weight". You start to blame yourself. It doesn't help that books of old blame dysfunctional families - although I've met lots of parents of sufferers and we all absolutely love our daughters.'

But Emma Healey, director of operations at Beat (formerly the Eating Disorders Association), insists anorexia is not caused by a case of 'bad parenting'.

'Parents often blame themselves. They think they should have spotted the signs earlier,' she says. 'But if you're living with someone it's hard to notice they're losing weight, especially if they start wearing baggy clothing to disguise it. Until you know the signs of an eating disorder they're very hard to spot because they resemble normal teenage behaviour. For example, the child will withdraw, wanting to spend more time alone.'

Dr Alex Yellowlees, medical director of the Priory Clinic in Glasgow, explains that the genetic component in anorexia sufferers is tiny. In other words, there is no 'anorexia gene' as such. He attributes the cause of anorexia to a combination of factors.

'Those at high-risk are people with low self-esteem, who share personality traits such as perfectionism and the tendency to obsess,' he explains. 'They tend to be high-achievers who are overly-controlled in their approach to life.'

He said people often develop anorexia as a coping mechanism in the wake of a stressful life event, such as a death in the family or leaving home. And as Olivia Newton-John has learnt from her daughter's ordeal: 'Eating disorders are usually nothing to do with food.' The illness is about using food as a form of control.

Jo, who has written a book with Alice about her struggle with her illness, understands only too well that control plays a major part. 'She became so ill we had to admit her to a clinic and she came out with this rigid meal plan' says Jo, 52. 'Every meal was weighed to the last gram. I had to measure her breakfast before school, meet her for lunch to make sure she ate. In the evening she'd exercise in keeping with a strict regime, before supper.

'With the benefit of hindsight I can see she's always been a high-achiever with a perfectionist streak and that's where the control element came in.'

Alice was 14 when she began withdrawing. When her periods stopped and she started drinking copious amounts of water, Jo initially thought she might have diabetes. Alice, who also suffers from Obsessive Compulsive Disorder, was eventually admitted to a clinic after eight months.

'It was harrowing for the whole family,' says Jo. 'You slowly begin to click it's anorexia and then you think "What can I do?" Meal times are a nightmare. You're terrified. You can't believe what's happening and you feel isolated and lonely.'

Jo says it's all too easy to see the underlying causes now. She says that while images of skinny celebrities in the media make recovery '100 times harder', Alice's anorexia did not stem from a desire to be size zero.

Jo believes that for Alice, it was her way of coping with feelings of loneliness after her two elder sisters, Beth, now 27, and Jenny, 25, left home for university.

'She missed them like mad, and they left as Alice was hit by puberty. It all came at the same time, and combined with her OCD, which she developed at 11, she became anorexic as a result.'

Alice is now 20, and Jo is quietly confident her daughter has overcome the illness. But she warns: 'I would say Alice is in control of her anorexia but it's still a fight every day.'

Alice in the Looking Glass: A Mother and Daughter's Experience of Anorexia, by Jo and Alice Kingsley is published by Piatkus.