Do you eat to live - or live to eat? That old 'trick question' isn't so popular these days; healthy nutrition and control of body weight have become serious subjects - and what starts out in innocence just to get a quiet party going can easily trigger endless discussion about bathroom scales and the latest fashionable diets!

A friend of mine devised a similar 'ice-breaker' which, he believed, carried no dangers of that kind. "Do you eat to die - or are you merely dying to eat?" Nothing more than a joke, he maintained. Nobody could take this question seriously, because 'eating to die' is demonstrably a preposterous idea. Whoever would behave in such a ridiculous way?

The shocking answer is that some people do. It's quite on the cards you’ve met one or more - but almost certainly without knowing it. You will not see them practising over-indulgence at table, because they never do so in front of others. Shape rarely betrays the nature of their problem, because few of them become obviously fat. Theirs is a peculiarly secretive disorder, a debilitating private hell. And whatever they do eat for, it isn't the joy of living well.

At the age of 26, Claire came to see me in the hope that hypnotherapy might help her. An attractive woman, by no means obese, she told me a distressing tale. During her teens, she began to experience occasional cravings for food, which drove her to raid the fridge and guzzle furiously until she felt sick. As time passed, her 'binges' became more frequent and she started to put on weight. Friends advised her to go on a diet, which she did - reducing her lunches at work to small portions of salads washed down with fruit juices. To everyone else's satisfaction, her weight stabilised; but the binges continued at least once every day - and by this time regularly went on until she threw up.

Despite being disgusted by her own behaviour, she couldn't stop it. "I had this feeling it was somebody else gorging and vomiting," she told me. Ordinary life began to disintegrate. Out of guilt she would make excuses and sneak away furtively from her office to gorge herself, frightened that she could suddenly lose control of herself; as a defence, she shied away from social encounters and lost most of her friends. Inevitably, there were problems with digestion and bowel functions; but she did not reveal the whole truth to her doctor, and medicines hardly helped. If only I could stick to a diet like all the other girls," she said, "things might get better. But I can't go on like this. I just don't know where to go."

Bulimia, so vividly described by Claire, is no joke. In some cases, it's true, the problems spontaneously disappear without any outside help; but these 'lucky' victims usually fall into another pattern of irrational

Many weeks after I met Claire, she wrote: ‘I’ve changed so drastically... I've not binged once. I can hardly believe what I did to my body for almost half my life ... it goes without saying that I am saving a fortune on my food bill too!'

Why is hypnotherapy so often successful in treatment of bulimia? For an explanation of that, we must delve, not into the realms of mystery and magic, but into the much-neglected psychology of eating.

At the start of life, a healthy baby probably does consume precisely the nutrition it needs, day by day. Before many months have gone by, however, satisfaction of mother becomes just as important as the child's own sense of repletion in determining when a meal is over. Giving that satisfaction brings rewards. "Eaten up your dinner? There's a good girl!" Praise is enjoyable, a hug and a kiss even more so. They all express love.

Parents come to advise children that they must eat 'properly' using the rational argument that growing bodies need nutrition. But growing bodies are guided by emotions, including the dark fear that not eating up will lead to disapproval and loss of love - unthinkable miseries! The habit of associating emotional rewards with acceptable performance at meals is thus firmly in place from an early age.

As a toddler advances towards maturity, the link between eating habits and emotional advantage becomes ever more complex and strong. Taking food evolves into a social business; those with good manners gain approval, those who guzzle like dogs at the dish or chew with lips apart are prone to rejection. Everyone has to realise that too large a portion implies greed - and too small offends the cook! As any psychologist will confirm, the appetite of the adult is all about nourishment of the whole person - and very little directly to do with nutrition for the body.

We learn to eat - or over-eat - habitually to please others as well as ourselves. In short, we eat to be lovable; and, if not actually loved, at least to be comfortable.

But by no stretch of the imagination could Claire have been pursuing an emotional advantage. Nobody can binge and gorge - secretively and in the middle of the night - in order to be loved or comfortable; there's nothing less lovable than a person who eats deliberately to be sick. The bulimic ravenously swallows food, not to sustain but to destroy.