Tackling the tyranny of thinness is a current preoccupation of politicians, celebrities and some in the fashion industry. A size-zero culture in which we are exposed to skeletal catwalk models and unrealistic images of skinny perfection is deeply damaging, we are told, and is creating a generation of girls prepared to starve themselves to conform.

But according to a study by researchers at Harvard University, published in last month’s Biological Psychiatry journal, both men and women are more likely to gorge themselves and become fat than to succumb to anorexia or bulimia.

James Hudson, Professor of Psychiatry at Harvard, and his colleagues surveyed more than 9,000 adults over two years and concluded that binge-eating disorder [BED] — a condition in which sufferers regularly gorge without purging — was almost five times more common than anorexia nervosa, and more prevalent than both anorexia and bulimia combined.

Binge-eaters accounted for 3.5 per cent of females and 2 per cent of males in the sample, while anorexia and bulimia nervosa afflicted less than 2 per cent of women and 1 per cent of men. Professor Ulrike Schmidt, head of the eating disorders unit at the Institute of Psychiatry, King’s College London, says that the figures for the UK are similar.

Although BED appears in the American Psychiatric Association’s Diagnostic and Statistical Manual of Mental Disorders , regarded as a medical “bible” worldwide, Professor Hudson says that until now it has been “strikingly underappreciated”. Less than half of the patients he questioned were receiving treatment.

This view is shared by other experts in the field. Dr Timothy Walsh, director of the eating disorders unit at the New York State Psychiatric Institute at Columbia University, says that the Harvard findings are significant. “They confirm that anorexia and bulimia are uncommon but serious illnesses, especially among women,” he says. “Many more people are troubled by binge-eating, and there is a need to understand this problem better.”

The Harvard study also found that, whereas the average duration of anorexia was 1.7 years, for BED it was 8.1 years. “Contrary to what people may believe, anorexia is not necessarily a chronic illness. In many cases it runs its course and people get better without seeking treatment,” says Professor Hudson. “But binge-eating disorder affects more people and tends to persist for longer.”'

Sharon Rother, of the obesity and eating disorders research unit at the University of Hertfordshire, has done extensive research into BED. She says: “Because anorexia is awful in the extreme and aesthetically alarming, it has achieved an almost alluring and sexy image in the media — people are intrigued by how others can starve themselves to such an extent.”

Those with BED, on the other hand, face the social stigma of fatness — although figures released by the Government last year indicated that being overweight is now the norm in the UK: two thirds of men and almost 60 per cent of women were officially classified as “unhealthily heavy”.

But, says Rother, there are crucial differences between BED sufferers and the growing number of people whose expanding waistlines can be blamed simply on gluttony and laziness. “This is not just a matter of eating too much every now and then,” she says. “There are defined symptoms and psychological patterns that make it an eating disorder.”

For BED to be diagnosed the patient must eat an excessive amount, usually within a two-hour period, at least twice a week for six months, and must experience considerable and mounting distress about their behaviour.

“There is a feeling of complete loss of control,” says Professor Claus Vogele, director of the clinical and health psychology research centre at Roehampton University, Surrey. “Without the compensatory behaviour practised by anorexics and bulimics, such as fasting or purging, BED patients often end up overweight or obese, which only heightens their anxious state of mind.”

Although they may seem poles apart, BED and the other eating disorders do have similarities. It is no surprise, say experts, that 36.6 per cent of binge-eaters in the Harvard study had previously sought help for emotional problems: those vulnerable to eating disorders are known to have lower-than-average feelings of self-worth.

“A lot of the underlying issues with all three eating disorders are more or less the same,” says Professor Vogele. “Like anorexics and bulimics, most BED patients report intense negative thoughts about their bodies. These thoughts are linked to low self-esteem, yet paradoxically the only way they can obtain short-term relief is to indulge in food. That produces feelings of guilt and loss of confidence — which increases the urge to binge again. It becomes a vicious circle.”

Tracing the precise roots of BED is an arduous task, though, as the relative influences of environmental and genetic factor are unclear. Professor Hudson’s previous research indicated that there was a genetic component to the disorder — family members of obese BED sufferers were twice as likely to have a binge-eating disorder as relatives of obese individuals who had no history of binge-eating.

In the latest study, he found that anorexia, bulimia and BED are often accompanied by other psychiatric problems such as phobias and depression. Overall, 79 per cent of BED patients had been found to have at least one other psychiatric condition.

Professor Hudson also suggests that, given people’s tendency not to discuss their eating disorders, “the true prevalence of BED is probably higher than reported”.

The long-term health risks of BED are those most commonly associated with clinical obesity, including high blood pressure, high cholesterol and heart disease. The condition has also been linked to infertility among female sufferers: researchers at St George’s Hospital in London have suggested that binge-eating might be a cause of polycystic ovary syndrome (PCOS), which affects between 3 and 8 per cent of women and can result in spots and facial hair as well as sub-fertility.

Binge-eating also causesa surge in blood glucose, which stimulates the pancreas to produce insulin — the hormone that regulates the amount of glucose in the blood. This means that after an initial “high”, blood sugar levels fall rapidly — which in turn sends a message to the brain telling it that the person needs more food to top up their glucose levels. Cravings for sugary foods that provide a quick glucose “fix” continue, so binge-eaters may eat a lot even when they are not hungry.

Katie Leonard, 35, from Southampton, is a member of Overeaters Anonymous (OA), a self-help organisation that runs 200 meetings a week around the country for people with BED and related problems. A binge-eater since her teens, Leonard has seen her weight fluctuate by 11st (70kg) and has suffered prediabetic glucose intolerance and osteoarthritis in both knees as a consequence.

“For years it was my ‘dirty secret’, something I did in private and tried to hide from my family,” she says. “My eating patterns were similar to the drinking patterns of an alcoholic. I would become obsessed with where and when I was going to have my next meal, and would stuff in huge amounts of chocolate, doughuts and ice-cream.”

With help from OA, she managed to cut out sugar two years ago. “As soon as I ate sugary things my appetite went haywire,” she says. “I would crave more and more food — and the bigger I got, the more unbearable my cravings became.”

Leonard has also had counselling and cognitive behavioural therapy (CBT), and her weight has fallen from 20st when she was at her worst. She is now “a fairly stable size 14”.

“One would normally try to break the vicious circle of bingeing,” says Professor Vogele. “Patients are encouraged to address self-esteem issues and to improve their communication skills in stressful situations, as binge attacks most often occur when they feel pressured.”

Sharon Rother hopes that increased awareness of the disorder will lead to it being spotted by more GPs. “It’s ironic that the pressures to diet and lose weight are often the trigger for a disorder that causes people to do the opposite,” she says.

“BED represents an emotional need and a degree of inner torment. The women and men who suffer from it are deeply pejorative about themselves and use food to mask their self-hatred, which only makes them feel worse. It is about far more than just being fat, and needs to be dealt with accordingly.”

Telltale signs of binge-eating disorder

You are obsessed with food and think about it a lot of the time You eat more than most people during the same period and in similar circumstances You regularly eat 2,000 calories at a sitting Your binges last for about two hours and occur at least twice a week for six months You feel that you have lost all control over your eating and can’t stop even if you try You eat a lot of food, fast, to the point of discomfort, even when you are not hungry. You binge alone, in secret, and feel embarrassed by how much you eat

WHAT TO DO

Keep a daily diary of what you eat, to identify any patterns and binge-triggers Eat regular meals. Doctors have found that this can reduce the number of urges to binge from 30 to four a month — so eat three times a day and don’t skip meals Learn how to spot and confront problems instead of seeking comfort in eating Contact Overeaters Anonymous (www.oa.org; 07000 784985) or Beat, formerly the Eating Disorders Association (www.b-eat.org.uk). Consult your GP if problems persist.