Fourteen million people in Britain are currently trying to lose weight.

In the second of a thee-part series on women and body image, Women's Editor Christen Pears explores the nation's obsession with dieting.

MARILYN Monroe: screen icon, sex goddess and size 16. Today, she'd be lucky to find a decent role among the ultra-slim leading ladies: Nicole Kidman, Julia Roberts, Cameron Diaz. Even the supposedly curvy Halle Berry and Catherine Zeta Jones are slender and lithe.

Twenty-first century woman is thin - or at least that's the image we're presented with every time we turn on the television or open a magazine. And the rest of us are desperately trying to conform. According to a survey published earlier this year, 34 million Britons are attempting to lose weight, spending £10bn on diet books, magazines, foods, supplements and pills in the process.

The diet industry is big business. Across Europe, the market for diet products increased from £56.6bn in 1998 to £62.3bn last year. It is expected to reach £67.7bn by 2007. But ironically, as the dieting industry booms, its customers continue to balloon. Half of Britain's women and three fifths of men are now clinically overweight.

Rates of obesity in Britain have doubled since the 1980s, contributing to rising rates of heart disease, diabetes and cancer, but at any given moment, about 14 million people in Britain are trying to follow a diet. Sixty per cent of the population try cutting their calorie intake each year but only one per cent achieve and retain a slimmer figure.

The latest sensation in the slimming world is the Atkins Diet, a controversial eating plan which cuts back on carbohydrates in favour of proteins. The book was originally published in the 1970s but has been at the top of Waterstone's bestseller list for the last five years. Three million people in the UK have tried the diet.

The regime has both ardent fans and detractors, and when some experts claimed it could be damaging to health, it sparked a national debate. The Government even issued a statement on the subject.

Julie Seed, a clinical psychologist at Northumbria University, is concerned about the phenomenon, which she says is evidence of the nation's growing obsession with dieting.

"The Atkins Diet is hugely popular at the moment and that worries me because there has been so little research on the physical and psychological effects. Women go on all sorts of diets: the weekday diet where you're good all week so you can eat what you want at the weekend or a diet to get into your bikini. But with all the hype about Atkins, people who have previously just meddled with dieting are now taking it seriously. It can lead to all sorts of problems in terms of physical and mental health. People who are dieting are eight times more likely to develop an eating disorder."

It is not difficult to see why. Cutting back on the amount of food you eat and depriving yourself of certain food types fosters an unhealthy attitude towards eating. It becomes disproportionately important, dieters begin to obsess and they experience feelings of guilt if they slip up. Some women find it spirals out of control and what started as an attempt to lose a couple of pounds becomes a full-blown eating disorder.

But the pressure to be slim is unrelenting. The average British women is a size 16 but the images we see in the media promote a slim, or even thin, silhouette. They present women with unrealistic role models, says Julie, and when they fail to achieve the figure they want, their self-esteem can plummet.

"Most models are very androgynous. They don't have breasts or the waist-hip ratio that was popular when Marilyn Monroe was around. They have a body mass index that places them clinically underweight. The vast majority of women will never achieve that weight and yet we still try. This means almost every woman is dissatisfied with her body in some way," says Julie.

"Every woman is different. We need to show a different range of sizes and stop the images that are being put forward at the moment. This obsession with being thin is society's monster and we have to address it as a society."

It has become almost the norm for British women to be following some sort of diet, whether that is a strict plan or simply cutting back on snacks. But constant dieting simply does not work, as rising rates of obesity show.

Jane North is a typical yo-yo dieter. Her weight has fluctuated dramatically since her teens and she has tried several diets, including Weightwatchers. Before getting married, she lost three stones on the Cambridge Diet, but that involved eating lots of meal replacement bars and drinking soup and once she began eating normally, the pounds crept back on.

Seven years ago, she lost eight stones with Slimming World but she has gradually put all the weight back on. At her heaviest, she weighed almost 18 stones.

But while Jane, who lives in Durham, is vivacious and outgoing, she is determined to lose her excess weight for good and has returned to Slimming World. In just ten weeks, she has lost almost two stones and she says she is already feeling happier and more confident.

"All I want is to be able to get back into a size 16, which means losing about five stone. I'm 40 this month and I always said I didn't want to be fat and 40. I'm not influenced by what other people think. I'm doing it for me, no one else."

Yo-yo dieting is extremely common but it can cause long-term problems, something that worries Mandy Drake. Along with sister June MacFarlane and friends Lynne Simmons and Julie Woodcock, she set up Darlington-based slimming club, Slimfit, now known as Changes.

All four had worked as slimming consultants for but found that, rather than losing weight, they were actually piling on pounds.

She says: "From my own experience, I know how easy it is to get obsessed with food and losing weight. I was desperately trying to find a miracle cure, a quick fix. That's what most slimmers are looking for.

"They go to a slimming club or on a diet and they're trying to get from A to B. When they get to B, they stop and all the weight goes back on. The next time they want to lose weight, it's more difficult and they find they have to go from A to C.

"That's when the problems start. If you starve yourself, the body doesn't understand it. It messes up your metabolism and as soon as you start eating normally again, you're more likely to put on weight. It becomes a vicious circle and you end up being more and more demoralised.

"We're not offering a quick fix and it isn't about depriving yourself of anything. It's about healthy eating. We teach people how to make permanent changes and stay slim for life, and hopefully that will stop people becoming obsessed with food."

* Next week: The children who crave to be thin