Faulty thinking: The pitifully thin experience themselves as overweight

There is a common misperception, found among both professionals and laypersons, that anorexia nervosa is a lifestyle choice, typically of young middle-class females who are so obsessed with their weight and shape that they practise extreme dieting and self-induced vomiting. Although most common in females aged 15-35 living in westernised societies, anorexia nervosa is occurring increasingly often in developing countries; it can also affect males and those in younger and older age groups. And far from being a lifestyle choice it is in fact an extremely complicated and life-threatening illness with a poor prognosis. Roughly 66 per cent of patients appear to make a full and sustained recovery after five years but the lifetime mortality directly attributable to the illness is in the order of 10 per cent. 

The disorder is riddled with misperceptions, mystery and paradox. The literal meaning of anorexia nervosa is "nervous loss of appetite", but that is a misnomer. In reality it is a biologically-based illness in which the sufferer usually has a ravenous appetite, as well as a myriad of other features that cannot be explained by starvation alone. This is the mystery of anorexia nervosa. 

Misperception is not confined to the unaffected; it occurs within the individual patient too. Patients with anorexia nervosa experience themselves as fat, even when they are very thin, a phenomenon known as body-image distortion. This is not a fabrication on their part, but a genuine misperception, which has been clearly demonstrated in numerous empirical studies-using mirrors, cut-out paper silhouettes and morphable computer images. A recent study has shown that when walking towards a narrow door, through which it is possible to walk directly, people with anorexia nervosa tend to turn their bodies sideways to go through the door, compared with healthy controls who have no such need, even though they are far less thin. 

Body-image distortion is only one of many complex and mysterious features of this illness. Other features of anorexia nervosa include: severe anxiety, an intense preoccupation with weight and shape, dread of weight gain, mood disturbance, self-loathing, obsessive-compulsive behaviour and a raised pain threshold. In addition, thought processes are often impaired. Sufferers may display a disconnection between thoughts and feelings, rigidity of thinking, difficulty inhibiting intrusive thoughts and weak central coherence. The latter refers to the fact that attention to fine detail is so pronounced in patients with anorexia nervosa that they lose sight of the big picture: they cannot see the wood for the trees. Numerous psychological tests demonstrate this. For example, when people with anorexia nervosa look at a complex diagram which contains a basic shape, such as a rectangle, in its centre, they cannot see the rectangle and focus only on the complexities of the diagram.