Stressed out? Worried about your weight? The last place you should go is the gym ...

They call them the "stressorexics", the Lycra-clad professionals who relieve the strain of high-pressure careers with regular visits to the running machines and weights rooms at the local gym. A bit too regular, it seems.

They call them the "stressorexics", the Lycra-clad professionals who relieve the strain of high-pressure careers with regular visits to the running machines and weights rooms at the local gym. A bit too regular, it seems.

According to the country's most respected advisory group for eating disorders, growing numbers of British adults are threatening their health with a dangerous combination of weight-watching and compulsive exercise.

The Eating Disorders Association (EDA) blames increasingly stressful lives and the growing emphasis on body image for this condition, which can push gym fanatics to the edge of serious eating disorders such as anorexia.

The Government's strong message on regular exercise, combined with the growing number of commercial gyms, could even have a detrimental effect on some, says the association, particularly those susceptible to eating disorders.

Although eating disorders are seen predominantly as teenage conditions, there is anecdotal evidence that growing numbers of women are now developing them in their twenties.

Susan Ringwood, the chief executive of the EDA, says:: "Going to the gym is always seen as a good thing. People don't think there are negative sides to this. There is no criticism if you go to the gym four or five times a week. The message about constant dieting being unhealthy has been listened to, while 'exercising' is still seen as healthy, in all circumstances," she says.

The EDA believes that the phenomenon - overexercising to control body weight - is not always understood by the medical profession. As a result, eating problems go undiagnosed and untreated.

Sam Baker, the editor of Cosmopolitan magazine, says that young women are increasingly stressed because their work and social lives do not match their expectations.

"Stressorexia is a product of our perfectionist society. It is a way that some young women cope with stress in their lives. It's not anorexia - it's a way of coping with stress that is eating-disorder-related," she says. Cosmopolitan investigates the issue in its January edition, out next week.

"It's not good to be normal any more," Ms Baker says. "People want to be special. This is about having huge expectations and aspirations - when you fail to live up to them you seek refuge in diet and exercise. It's a real growth area. It is the last taboo of eating disorders because it's not about teenage girls."

The fitness industry claims 6 per cent of Britons are now gym members, while the number of private health clubs with more than 500 members is nearly 2,000. This rise in the number of gyms and health clubs, eating-disorder experts claim, has made it easier for people to over-exercise.

Rob Coster, the fitness manager at the Esporta Health and Fitness Club in Guildford, Surrey, says his staff are trained to watch out for the minority of people who over-exercise and insists on rigorous induction courses for new clients.

"I've seen this happen at several different clubs," he says. "We try to catch it early. Exercise is a great way to relieve stress, but it can be taken too far."

The fitness industry is gearing up for its busiest time of the year as millions make New Year resolutions to get into shape. The Fitness Industry Association (FIA) says only a small number of gym patrons would be in danger of developing stressorexia. "Not enough people do exercise," says Innes Kerr, the FIA's membership services director. "Our primary concern is to get more people more active, more often. If a small minority get excessive, that's a risk, but we're not aware of any evidence that shows it is a major problem."

Are you stressorexic?

• Do you exercise to help control the way you feel, especially if you are angry or sad?
• Do you feel anxious if you can't take exercise you had planned to do?
• Do you ever exercise when you know you are ill or injured?
• Is your main reason for exercising to control your weight and change the way you look?
• Do you often take exercise instead of dieting to compensate for eating too much?

According to the Eating Disorders Association, if the answer to three or more of these questions is "yes" you are at risk of overexercising. Your fitness regime could be a response to low self-esteem rather than a healthy enjoyment of physical activity.

'I was going to the gym for up to two hours a day'

Janet Miller, a 30-year-old writer, explains how she became an exercise obsessive

"A tactless comment from a boyfriend led me to hit the gym. I'd never been a big fan of exercise, but I knew that diet alone wouldn't get me the body shape I desired. At first, I did the recommended three to four visits a week, combining 40 minutes of running, cycling and rowing with 20 minutes of weights. I was unhappy with my job and home at the time, and exercise cleared my head.

"Soon I was there for up to two hours a day. Some days, I'd also do an aerobics or dance class. I got a buzz from pushing myself harder. Despite increasing my energy output, I continued to reduce my calorie intake. My weight plummeted. I both loved and loathed my tiny size eight body.

"People were telling me that I was getting too thin, but I didn't want to listen. Soon afterwards, my periods stopped.

"Six months later, I was promoted at work and moved house. I was too busy to get to the gym every day and one of my new housemates was a chef who often cooked for everyone. Feeling happier, I began to put on weight and my periods returned. I stopped going to the gym completely. Within a couple of months, I was heavier than before.

"Nowadays, I'm a curvy size 10-12. I'd love to be slimmer, but I try not to obsess over it. If my clothes are tight, I cut back on fast food and walk instead of taking the car."

Additional research by Fran Yeoman