Dance and fashion have so much in common. Both are body-centred. Both involve performance, display and self-expression. They also share a dark side - a potentially fatal obsession with weight and body-image. Since the cultural revolution of the 1960s, female dancers and fashion models have presented near-identical symptoms of damage, with failure to live up to extreme physical ideals resulting in drug and medication abuse, mental health problems and even death from starvation. Three models (Eliana Ramos, Luisel Ramos and Ana Caroline Reston) have died as a result of eating disorders in the past eight months, and last month it was announced that Allegra Versace, 20-year-old fashion-student daughter of designer Donatella Versace, had been struggling with anorexia 'for many years'.

While fashion is on the rack, however, dance has moved on, establishing a new and liberating aesthetic which puts it way ahead of the curve. The size issue has been confronted, dance is in recovery, and as performers like the Royal Ballet's Laura Morera, Rambert's Mikaela Polley and Angika's Mayuri Boonham attest, the medium has become a celebration of women's experience, intelligence and power. How did this happen? How did a minority art-form come to make fashion look so unfashionable? How did strong come to be the new thin?

I was a ballet student in the 1970s, when things were very different. Thinness was everything, the manifestation of an extreme aesthetic which idealised the ethereal and shrank with horror from the 'civilian' body-shape. All female ballet dancers subscribed to this ideal but it was never made clear how it was to be achieved. There was no nutrition advice or counselling, no understanding of the effects of dieting on the adolescent body. Instead, everyone smoked like chimneys, and many of the girls lived on little more than cottage cheese and black coffee. There was also an unofficial, semi-secret trade in 'slimming pills' (actually amphetamines), for those vital crash weight-losses before Solo Seal exams or company auditions.

Clare Park was in the year above me, and severely anorexic. 'No one talked about the state I was in,' she remembers. 'There was no support. And I was only 16. The school's attitude was: if people fall by the wayside, too bad. There's always another dancer waiting to take her place.' Park left ballet, became one of the most iconic fashion models of the 1980s and is now a photographer. A self-portrait, inspired by her memories of anorexia (in a box, naked, with her mouth bandaged), became the cover-image of Naomi Wolf's The Beauty Myth.

For us boys, never giving food a second thought, female body-angst was part of the wallpaper: always there, never directly addressed. We were vaguely sympathetic, but there was stuff we didn't want to know, like when a friend, after a birthday blow-out at Patisserie Valerie in Soho, breezily announced that she was going downstairs 'for a quick chuck' as she had a costume-fitting that afternoon. For all its weirdness, I loved my time as a dancer, but it was not, overall, a happy world. Four colleagues I knew well died of heroin overdoses.

In 1986 the American ballerina Gelsey Kirkland published a tell-all autobiography, Dancing on my Grave. Recounting her personal history of self-hatred, casual sex, cosmetic surgery, anorexia, bulimia and cocaine addiction, Kirkland flagellated the US dance establishment, particularly the choreographer George Balanchine, who she claims fed her amphetamine 'vitamins' on tour, and her ex-lover Mikhail Baryshnikov, whose narcissism supposedly drove her to the point of breakdown.

This was the dance-scene of the time laid bare - an extreme but just-about recognisable portrait to those of us who inhabited it. The book didn't go down well with Kirkland's colleagues; many felt she had said the unsayable and let the side down. For Toni Bentley, who danced with her at New York City Ballet, it is 'the miserable manifesto for all those who wish to perceive ballet dancers as victims... She does not speak for the ballet world at large and most certainly not for the experience of most of us in it'. Everyone in the dance world read it, nevertheless, and took note. Anorexia, ballet's guilty secret, was finally out in the open.

In 1997 Heidi Guenther, a 22-year-old dancer with the Boston Ballet, collapsed and died from complications arising from an eating disorder. Her death served as a final wake-up call, and recent years have seen a major change in schools' and companies' perception of their duty of care. The gothically skinny 'bunhead' with her sunken cheeks and freaky eating habits - once such a staple character of ballet schools and companies - is now very much out of favour.

'If a girl or boy looks too thin or unhealthy, they are not allowed to perform,' says Jane Hackett, director of the English National Ballet School in London. 'As performing is the main motivation for these young, talented people, it quickly has the desired effect.' At the Australian Ballet School in Melbourne, resident psychologist Lucinda Sharp agrees that the days when dancers lived on cigarettes and coffee are over. 'There was a time when very, very skinny dancers were fashionable, but we have a very strong holistic approach to the health and welfare of our students.' At the Melbourne school, as in London, students aren't allowed to perform if they fall beneath a healthy weight.

There are still thin dancers in ballet; Darcey Bussell, for example, has always performed at a very low body weight. But ballet is only a part of dance, and thin is no longer the standard. Tamara Rojo, the Royal Ballet's finest ballerina, is plushly curvaceous. She looks like a real woman, and her performances are all the more believable because of it.

If there's a physical ideal in dance now, it's one of sleek, streamlined, long-muscled power. Forget the vaporous sprites of yesteryear, today's dancers are as likely to be lifting the men as being lifted. Look at the women in British ensembles like Random Dance or the Henri Oguike Dance Company. Look at Sylvie Guillem with her ripped physique and steely limbs. They're amazing. Like comic-book heroines, like Promethea or Lady Deathstrike. What dance has achieved, and fashion hasn't, is a change in its core aesthetic. Strength is a democratic ideal, because anyone can be strong - anyone can be a super-version of themselves.

This change hasn't been overnight; it's been unrolling for decades. For me, as a ballet student, escape from one-track Swan Lake madness came in the form of my evening job as an usher at Sadler's Wells. We had 'contemporary' classes at school but nothing that prepared me for what I saw in the theatre's contemporary dance seasons - avant-garde events by choreographers like Louis Falco and Jennifer Muller in which all the rules, and especially those governing body-image and gender roles, were torn up and thrown to the winds.

In Muller's Strangers, described as an 'accidental confrontation with the audience', dancers screamed, fought and took showers on a stage overrun with chimpanzees, as Molecular Madness belted out Burt Alcantara's score at ear-bleeding volume. Equally vivid memories linger of Robert Cohan's Stages, a writhe-fest performed to pulverising vocals by Whorefying Experience. This was a parallel education, and a thrilling one, and its stars were fearless, do-anything types like London Contemporary Dance Theatre's Linda Gibbs, Rambert's Lennie Westerdijk, and Nederlands Dans Theater's Mea Venema. Those women, and others like them, remade my perception of the female dancer.

They also reflected a historical process. Since the 1960s, especially in America, increasing numbers of women had been turning to choreography and taking control of the dance-making process. Trisha Brown, Twyla Tharp and others had no time for the traditional, passive image of the female dancer: their performers were athletic, assertive and pro-active. A key moment in dance's representation of women occurred with Yvonne Rainer's Trio A (1966). Requiring strength and mental acuity but no special dance skills, the piece displayed Rainer's ordinarily proportioned female body as a thing of wonder, inseparable from the intellect which informed it.

European choreographers like Pina Bausch and Anne Teresa de Keersmaeker have played equally important roles in the evolution of the female dancer, consistently recruiting strong and articulate (rather than dainty and 'feminine') women. In 1987 the Swedish choreographer Mats Ek produced his Swan Lake, in which a cringing prince is pussy-whipped by a vengeful Amazon of a swan-queen. Ek's ballet contained several male swans, and in 1995 Matthew Bourne made all of his swans men. Their gender, however, was not the point. The important thing was the aesthetic. Power had replaced delicacy.

As yet, fashion shows no sign of following dance's example. In September the New York Times carried a report on catwalk models 'so gaunt and thin that their knees and elbows were larger than their concave thighs and pipe-cleaner arms and their bobbling heads looked as if a slight breeze could detach them from their frail bodies'. As dance once did, fashion continues to view the image of the physically and emotionally adult woman with horror. If there is to be a change in aesthetic, however, it's precisely those adult women who must initiate it, as they did in dance. With luck, there's a generation of whip-smart new designers out there, waiting to kick the old order into touch. Waiting to prove, as in dance, that strong is the new thin.

Mayuri Boonham, 36
Angika Dance Company

I was born in Birmingham, and was sporty at school. Captain of netball! I was tall for an Indian girl - 'Where are we going to find you a husband?' my parents used to say despairingly - and I was dark-skinned. I was aware very young of the hierarchy of shades of brown. The ideal look was fair... so I took up sunbathing! I'm fine with the way I look.

I always admired Bollywood dancers, the way they moved, their womanly figures, and I used to create my own shows in the living room. At 13, I began to study Bharat Natyam (North Indian classical dance), and I've been studying, performing and choreographing ever since. My guru is Prakash Yadagudde. I got married at 21 [to the sculptor Nigel Boonham] and this enabled me to pursue dance single-mindedly. Without Nigel - no career. I owe him everything.

Anglo-Saxon supermodels are like another species to me. I've never admired thinness, and I don't identify with the images in fashion magazines. I analyse what I see intellectually and move on. Abnormally thin people are just ugly. I see someone in the skinny jeans, the shoes, carrying the expensive handbag, and I think oh no. They've fallen for it.

As a dancer, you have to control your diet, but technically and responsibly. You also need fitness of mind - at the moment I'm reading a book about mathematics, Bob Dylan's autobiography and a Salinger novel. It's harmony of the body, mind and feelings that brings dance alive. You're trying to transcend your physical form. Right now the company's just back from Germany. A sell-out tour of our Urban Temple programme. It was fantastic, but it was hard work. You've got to be strong.

Laura Morera, 29
Royal Ballet

I lived at home in Madrid until I was 11, then went to the Royal Ballet School. I was very homesick, I didn't speak English, and I didn't have that slender British look. In Spain you're doing fouettes (advanced turns) by the age of nine, and I was muscly. I've had to learn how to avoid muscle-bulk, to lengthen the body out, to balance strength against line.

My ideal at school was Darcey (Bussell). Beautiful, tall, glamorous and strong. Later, though, I realised that picture-icons are negative. You have to be your own icon. Beauty comes from happiness, and I'm happy with the way I am. There are things I'd change but I've learnt to meet myself halfway. If I look at my body it's for dance, not fashion. I don't have any vanity but I'm a perfectionist, professionally speaking.

I look at fashion magazines and frankly I don't know what designers are thinking. To look like some of the models you'd have to be half-dead; I get angry that designers play with people's lives that way. And the editors make me angry too: you see a picture of some celebrity, she's clearly anorexic, and they put her in the best-dressed list.

The truth is that if you become half a person in weight, you become half a person in spirit. So for the sake of my relationship (with dancer-fiance Justin Meissner), I stay whole. I feel passionately about this, and I want young dancers to know that, yes, you have to make sacrifices, but at the end of the day we're not models - we need strength.

At the Royal Ballet no one's fanatical about your weight and look - they want you how you are. That's why Britain is the most theatrical country in the world. I'm truly spoilt here.

Mikaela Polley, 35
Rambert Dance Company

I grew up in Essex and trained locally and at the Royal Ballet School. A friend had anorexia; it was horrifying seeing her mother having to feed her up before dance competitions. Some girls at the Royal were on the thin side. We had no nutritional information given to us. We were very aware of our body-shapes though - everyone wanted longer legs and slimmer calf-muscles. My strength was jumping; I was always very toned.

I joined Birmingham Royal Ballet, but I was always picked for the modern stuff. I felt more comfortable with it, there was something to attack, something with real physicality. I joined Rambert in 2001. There was more individuality among the female bodies. At 5ft 3in I was one of the smaller ones but my upper body strength grew fast, and that was fine. I've always felt confident about my body, and content with what I've been given - breast size, bum size and so on. I've put my body through a lot as a contemporary dancer, but I've come out fairly unscathed.

You can tell when women are underfed. You see the legs; they're all knee-cap. You can tell from the chest-bones and those thin arms. Looking at other female dancers, I'm moved by people who are grounded, who can move through space, who have weight. I like to appreciate that it's a woman on stage.

Right now we're rehearsing Anatomica #3 by Andre Gingras, which sees bodies as exhibition sites. We're looking at people who exhibit themselves - politicians, models, porn-stars - and at new and extreme ways of presenting the body. It's a high-energy, very physical work. All of us are strongly influenced by performers: they have power, negative as well as positive.

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