Linda, who is the only daughter of strict parents, was brought up in a small country town.

As a girl, she was shy and withdrawn, an obedient daughter and a conscientious scholar.

Although she had no intimate friends, she considers her childhood to have been happy. Her physical health was good, and she was of normal body weight.

At 17 years of age she went to university to study biology. Her parents moved to the city so that she could continue to stay at home.

In her second year she met her first boyfriend. Her relationship with him grew increasingly intimate, until eventually he asked her to have sexual intercourse.

She refused, they argued, and he walked out on her. She was deeply distressed, and was tearful and de-pressed for some weeks.

She worried that perhaps she had been wrong to refuse sex, but also felt guilty about the heavy petting that had occurred.

It was at this time that she starred to diet. Initially, she thinks, not eating was a way to show her parents how miserable she felt.

But soon she became preoccupied with thoughts of food, and with not eating.

She stopped taking meals with her parents, and restricted herself to foods low in calories but relatively high in proteins and vitamins.

She worked out a strict regime of eating, and if she deviated from it she would punish herself by missing the next meal completely.

Her menstrual periods ceased and her weight fell rapidly to about 60 per cent of normal.

Over the ensuing seven years, Linda has had a successful academic career, but socially she has become increasingly isolated, and has had no further boyfriends.

Besides work her only real interests are food and dieting, and she has developed a series of rituals associated with eating.

She realises that she is too thin and admits that she feels hungry but will not allow herself to ear normally.

Although she knows it is ridiculous, she thinks of herself as being overweight, and is terrified that she may become obese.

Linda’s not eating has become the most important thing in her life, and in that of her parents. Literally she lives in order to diet.

The next case is somewhat unusual in that the person concerned is a young boy.

Tom is the son of a burly farmer and his buxom wife. His early development was normal and he was an active, outspoken boy.

When he was 11 years old, he decided to become a jockey. His friends teased him about his ambition, saying that he would grow up to be like his father, too heavy for riding.

Although he had never been obese, Tom suddenly started to diet. His whole personality seemed to change.

He became withdrawn and depressed, disobedient and stubborn, and preoccupied with his weight.

A year later he was very thin and ill. He was admitted to hospital, and while there he stubbornly resisted taking food again.

He exercised himself strenuously, and induced vomiting. He developed a series of medical complications, some of which were particularly severe.

With intensive treatment, he regained a little weight and was discharged. A few months later, he was readmitted in an emaciated state.

On this second occasion a dramatic change came over him after he had again regained a little weight.

He said that he was not able to understand his previous behaviour, that it had been ridiculous and that he now wished to return to normal weight.

He ate normally and was soon back to a healthy physical condition. Since leaving hospital eight years ago he has remained well, and has grown into a happy and active young man.

Mrs D. is the daughter of a clergyman and his wife. Her childhood was unhappy, with much conflict between herself and her parents.

Both her parents were overweight and she herself was grossly obese at the age of 14 years. She was teased about her obesity, which she found particularly distressing, as she had a lively interest in the opposite sex.

She attributes her subsequent low self-esteem to her unhappiness at this time.

Throughout her teens she tried unsuccessfully to control her weight by dieting.

A 17 years of age, she realised that self-induced vomiting and purging were effective means of bringing about weight reduction.

She learnt to regurgitate after meals, and developed a pattern of behaviour which consisted of gorging herself with rich foods and then vomiting. Her weight fell dramatically and her periods ceased.

She married in her early teens. Her husband is a rather pedantic and precise man. He accuses his wife of deliberately using her eating difficulty as a means of manipulating their social life, for instance, to avoid going our.

Both parties complain that they do not find their sexual life satisfactory. Over the years, Mrs D‘s weight has gradually returned to normal. She is now aged 29. She still induces vomiting on three to four occasions each day and takes between 100 and 200 laxative tablets daily. She is disgusted by her behaviour, but is afraid that if she abandons it she will be unable no control her eating again and become obese.

"The cult of thinness provides a context for these problems. Refusing food is one way of exerting control," Dr Paxton said.

But while anorexia nervosa was most common in post-pubescent adolescent girls with a distorted perception of body image, the latest statistics showed that one in 10 sufferers was male.

"Teenagers go through a period of changing body image and they are often acutely self-conscious about their appearance.