The well-built man, complete with six-pack and muscular shoulders, is no longer the ideal male body shape. But when did men start aspiring to be thin? And should we worry?

Are men more body conscious now than they were 10 years ago? Apparently yes. Infinitely more. They're certainly subject to increasingly proscriptive and exaggerated notions on the physical ideal. Rootstein's spindly Homme Nouveau shop window mannequin (27in waist, 33in chest), and Burberry's fit model, cast according to the equally slender proportions of male model Davo, are merely the latest, most headline-grabbing manifestations of the mounting pressure on men to be a certain – diminished – shape. Consider, for example, that the average British man has a waist size measuring 39in, and yet American Apparel – spiritual home of anyone hoping they might be even the teensiest bit hip – doesn't sell its signature Slim Slack trouser with a waistband larger than 30in. Consider a significant proportion of contemporary male cultural icons: Russell Brand, Pete Doherty, Matt Smith and David Tennant, Alex Turner of the Arctic Monkeys, Johnny Borrell of Razorlight, nearly all of the Kings of Leon, Nicholas Hoult, any one of the men with whom Kelly Osbourne periodically dallies… Thin, thin and thinner.

Do men – normal, non-celebrity, non-model men – care? Well, yeah – apparently they do. Incidences of eating disorders in men are on the rise. In 1990, 10% of people suffering from anorexia or bulimia were estimated to be men; today it's more like 25%. Figures for women have remained steady throughout that time. Two out of five binge eaters are men. More and more teenage boys say they are dissatisfied with their bodies. The male segment of the plastic surgery market is booming – moob jobs are proving especially popular; in 2009 there was a 44% year-on-year increase in male breast-reduction procedures. So yes, men want to be thinner. Actually – men want to be thin.

And yet traditionally the male physical ideal is the opposite of skinny. It is athletic, buff, big shouldered, capable. It has pecs and guns and ripped abdominals. Until relatively recently, thin men were ashamed, or assumed to be ashamed, of their bodies. They were considered less masculine by dint of their thinness; the rare thin male cultural icons – Morrissey, Jarvis Cocker – made thin part of their shtick, an expression of how disenfranchised they felt, how removed from the cultural mainstream.

But now thin is the cultural mainstream. Thin is desirable. Men want it – men diet for it. They go under the knife in pursuit of it.

The skinny man movement began a decade ago, with an ideal created and perpetuated by fashion designer Hedi Slimane. In 2000 luxury fashion institution Christian Dior appointed Slimane creative director of Dior Homme, its menswear line; in 2001 Slimane showed his first collection. It celebrated a gobsmackingly lean silhouette. Slimane's aesthetic hinged on razor-sharp, super-tight tailoring; and jeans so clinging that they almost qualified as meggings (man leggings). It required a pallid, waifish, concave-chested teenage boy model to do it justice – models Slimane "street cast" by scouting the hipper districts of significant metropolises for Twiglet-form 16-year-old indie boys. Slimane's silhouette gained extraordinary currency – thanks in part to the fact that he made the professionally waifish and ineffably cool Pete Doherty his muse. It set the fashion world on fire; fashion elder statesman Karl Lagerfeld was so impressed that in 2001 he lost a third of his body weight – 90lb, more than six stone – for one reason only: "I woke up and decided I was not happy with my physique… I suddenly wanted to dress differently, to wear clothes designed by Hedi Slimane."

After that, Slimane's influence seeped into the non-fashion sphere, reconfiguring the aspirations of a broader market. Next thing you knew, the streets of our cities were overrun by slender-hipped teenage boys in skinny jeans, their fragile chests visible beneath the plunging "V" on their T-shirts, hoodies dangling off coat hanger-thin shoulders. Slimane left Dior in 2007, but the influence of his work for Dior Homme endures. Skinny is big.

WHICH IS NOT TO SAY that the cultural imperative to be extremely skinny has replaced the cultural imperative for men to be buff. It hasn't. The muscular male ideal has somehow, simultaneously, remained current. The publishing miracle that is Men's Health – a monthly men's glossy magazine which boasts robust circulation figures (more than 250,000 at the last count, the 16th annual increase in circulation) at a time when other men's titles are floundering – has built its brand on cover image featuring extremely well-toned blokes.

The most successful male model in the world currently is David Gandy, a ridiculously muscular Essex boy who made his name frolicking semi-naked in a rowing boat for a 2007 Dolce & Gabbana perfume ad. A year ago I interviewed David Gandy about his career. He told me he had no idea why he was suddenly successful – he'd struggled for a long time to get jobs in a fashion climate that favoured Slimane's skinny boys. "No one was using me, and my mum was going: 'I don't understand why! You're so handsome!' But I was like: 'Mum. There is a reason.' No one wanted the big guys. It was all the skinny, androgynous look. People would look at me very, very strangely when I went to castings."

Other people seemed to know why Gandy's look had started doing swift business. Model bookers, advertising execs and fashion editors agreed that a more robust physical ideal resonates culturally during recessions and times of political uncertainty; the times when we instinctively place more value on men who look like they could take care of themselves. "We saw exactly this in the last recession – and we also saw it directly after 9/11 . Clients stop wanting to take risks. They revert back to basics, to classic ideas of what's handsome," said model booker Heidi Beattie of Select, the agency that represents Gandy.

So we're left with two polarised ideals on masculine beauty. Hedi Slimane-endorsed skinniness via Homme Nouveau and Davo; and a strong, muscular, austerity-resistant Gandy-esque form. These ideals are somehow coexisting, pulling men in two different directions and filling their heads with a general sense that they are nothing if not completely physically imperfect. Cue eating disorders, a general sense of inadequacy, a new, horrible degree of self-consciousness…

What do women think of all this? I'll be honest: we have to work hard not to cackle, and scream: "Welcome to our nightmare, suckers!" We've been subject to these kinds of pressures for centuries, expected to grow and shrink and entirely redefine our body shape depending on prevailing diktats on what is and isn't hot. You, men, have not helped us with your endless, casual objectification, your porno-lite lads' magazines and your inability not to deliver a relentless commentary on every aspect of our physical being. We've struggled between polar physical ideals for decades: between the intimidatingly severe and extremely thin architecture of the catwalk model, and the super-tanned, curvaceous obvious pulchritude of the glamour girl. Relatively, you lot are amateurs at all this.

Do you know what it's like to turn 12 and find your body subject to the scrutiny of the entire world? Do you know what it's like to be constantly judged by the opposite sex and (perhaps more harshly) by your own? To be conditioned to view your body in such a way that you regularly find yourself in a public space (a park, a train carriage, or walking down a street) rating the legs, or bellies, or upper arms of everyone you pass in terms of the merits and failings of your own? Do you know how self-conscious that makes you, how disarmed, how confused, how dissatisfied, how unbelievably freaking vulnerable?

Oh, hang on! You do know now! It is tempting, as women, to respond like this. But it isn't kind, or even useful; society functions less well the more time its constituent parts spend fretting about the shape and placement of their bottoms, so let's not do that.

Let's instead consider the fact that women are not especially concerned by men's bodies, in and of themselves. We don't value buff or skinny in its own right. I'm generalising wildly of course – although it's an informed generalisation, based on 20 years at the coalface of men's bodies. That – and the fact that James Corden is something of a pin-up; that now-slim actor Seth Rogen is widely believed to have lost his appeal since losing the extra few stone he carried when he made his name as an unlikely romantic hero in 2007's Knocked Up.

Twitter agrees. I posted a tweet asking female followers how concerned they were by men's bodies, and 60-odd tweeted back to tell me how much more they valued some configuration of clever, sexy, funny and well-dressed. Many said muscular bodies were a positive turn-off, hinting at unacceptable levels of vanity; a few more said they rather liked skinny, although more again said skinny was fine as long as it wasn't skinnier than they were. "As long as his breasts are smaller than mine, he can be skinny or carrying a little extra weight," said one woman. "If over 50, must be fit. Don't care about handsome or bald… in fact, love bald, if also nebulously hot…" said another. "Would forgive any abdominal shortcomings for sexy hands!" said a third.

Most of us copped unapologetically to rampant heightism.

Women can appreciate a beautiful male body as part of a passable whole. But a body – whether it is fashionably slender, or Gandy-esque and buff – is certainly not worth more that an attractive face and a winning personality. Twitter made much mention of the Body of Baywatch, Face of Crimewatch physical phenomenon – all the women who invoked it said they were not prepared to compromise facial beauty for a good body, when looking for a mate, or even when looking for an inconsequential fling.

But if men are not obsessing over their bodies – reshaping them, hating them, wishing they were different, depriving them of food, cutting them up – in response to pressure from women, then why are they doing it?

Partly, you'd imagine, because of a general cultural obsession with youth. Men are not immune to increasing pressure to remain young-looking. The skinny ideal in particular is a supremely youthful prototype; barely pubescent. Rootstein justified its decision to launch the Homme Nouveau mannequin by explaining that it was designed to showcase clothes meant for young teenage boys. American Apparel has just launched a new trouser style they've branded the Schoolboy Pant.

But there's something bigger and more pernicious even than the cult of youth wielding its influence here. According to Matthew Todd, editor of gay style magazine Attitude: "It's clear that men are far more objectified than they used to be. Our bodies have been commercialised. When I was growing up, it was rare to see half-naked men in advertising; when you did, it seemed like more of a taboo. Now the male body is used to promote everything." Todd's absolutely right. Half of the moodily lit, kinda-erotic images used to sell us things now feature semi-naked men where once they only featured semi-naked women. Adverts like the Dolce & Gabbana Light Blue perfume film which projected David Gandy to fame (and also featured a woman – though no one can really remember who she was). The giant billboards filled with increasingly risqué images of sports stars, of Ronaldo, of Kaká, of Becks. The starkly lit snaps of bearded hip kids which American Apparel favours for its advertising campaigns. The nameless pretty boys in hairdos and homoerotic poses routinely employed to flog anything from pants to rollerball gizmos designed to diminish unsightly undereye shadows to sunglasses. In those images, these men – every last one of them, even the celebs – recline, supine. They are submissive. They gaze up at the cameras from beneath their eyelashes. They are beautiful, commercial coquettes; and they dictate the way we perceive the male form.

Does it matter? Yes, it does. As I've said, society doesn't function brilliantly when significant portions of it are hate their bodies. While men might better understand the pressure women experience to look a certain way as a consequence of all this, they might also end up too deeply mired in a netherworld of self-loathing to be able to do anything about it. The increasing prevalence of male eating disorders definitely isn't desirable. Sam Thomas, project leader of an organisation called Men Get Eating Disorders Too, says that while eating disorders develop for a complex combination of reasons, and cannot merely be assumed to be the consequence of a new type of shop-window mannequin: "Men are certainly under a lot more pressure to look good, to live up to the latest trends now than they were 10 years ago. There's an increased emphasis on male fashion and cosmetics, and this has affected how men perceive their bodies. It's made them more conscious of them… If a man is already feeling insecure about his body, exposure to such 'ideals' could make him feel inadequate and increase his susceptibility to eating disorders." No one wants a manorexia epidemic.

Yet it seems unlikely that this objectification and commercialisation of the male form will abate any time soon. Actually, it feels like it's only just getting started, gaining pace. Cristiano Ronaldo's new Emporio Armani underwear shots – released recently, to the rapture of the internet – are the latest evidence of that. We probably can't stop it; but the women among us can, at least, stop the vengeful sniping over it. As Attitude's Matthew Todd says: "I sometimes hear women say things like: 'It's great – men can get a taste of how it feels to be objectified as women have been for all eternity.' But really we should be working on a way to make it so that physicality is not the defining thing about any of us." Which, of course, we should. Instead we seem to be making it the defining thing about all of us.

Burberry's boy: putting the man into mannequin: Davo McConville describes a casting event



I stand in the centre of a workshop, naked except for skintight cycling shorts, surrounded by model makers. I'm coated with six tubs of Nivea moisturiser before layers of plaster are moulded to my body by John and Tristan Schoonraad.

Burberry is shooting coats for a new website. A plastic mannequin is needed to "model" the clothes, but the existing mannequins are too muscular for the Burberry ideal. Which is where I come in. My body will be the model for an all-new skinny mannequin.

I've been asked before whether I'm absolutely certain I don't have an eating problem. I'm sure I don't, but I do have very little meat on my bones. My body only decided to grow tall and long when I was past 17 and it resists developing muscular bulk. I've bought weight equipment; I've flirted with sickly protein powders. Nothing has altered my body. I am 6ft 1in, with a 35in chest and a 29in waist, and have the right body for the job. Even so, I don't know that anyone would consider my body archetypal or as an exemplar to work towards. You couldn't aim for this; it's defined by a vacuum of flesh, by what it's not.

I've worked for Burberry before. I spent an afternoon six years ago having test pieces fitted to my body. I was a clotheshorse for their fashion then, as I am today. My body was the point, rather than my face. Burberry's ideal is as tall a figure as possible, the slender body lending an elegance and a hint of androgyny to their tailored apparel.

As a model you quickly come to realise the utter objectivity with which others perceive you. Casting after casting in which one part of your appearance leads to rejection. Two castings in the last year have seen my body fail on exactly the point which won me this job. Both Wrangler jeans and Alexander McQueen's design house thought me too slender for their products (for Wrangler, my ass wasn't big enough).

At Elstree, I think back to a conversation with my agent about whether I'd be happy with naked work. I'm sure I said no, though modesty has no place in fashion. Life-casting goes beyond naked, into the construction of a replica self. I will leave behind two doppelgangers with removable arms. Life-sized voodoo dolls.

After being levered out of my second plaster cocoon, I'm given a plastic safety suit to wear for my walk to the dressing rooms to clean up. Any misconceived notion that my body might be some kind of ideal is destroyed by the facilities provided. The shower is too short. The cubicle isn't broad enough for my shoulders, to the point that I can't reach around to properly remove the dried plaster and Nivea from my pores. I go home (never needing to moisturise again) with the knowledge that there'll always be a 1:1 edition of me out there.

• This article was amended on 28 July 2010 to remove inaccurate identification of individuals said to have undergone body plaster-casting.

Through thick and thin: why size matters more to some men



Stephen Fry: "I was fed up with having man boobs. I could see silverback gorillas looking at me with envy."

Ricky Gervais: "I laugh about being fat, but I should be ashamed. I should walk down the street and have people shouting: 'Fatty!' That's what I want, to get me out of it."

Jarvis Cocker: "Why do they call a puny person a weed, when weeds are tenacious plants that grow in adverse circumstances?"

Gok Wan: "Growing up I was too busy trying to be the life and soul – the big happy fat character who wanted to be fat, wanted to be gay and wanted to be mixed race – to discuss being bullied with anyone."

Johnny Vegas: "When I'm out shopping I need XXX size clothes and in America it is the one time in my life that I can glance at people looking at the larger-sized clothing and think to myself: 'How did they let themselves get like that?'"

James Corden: "My weight was never a concern for me, because I could make women laugh."

Will Self: "For a period I was morbidly obese. I went out with a feeder."

Alan Carr: "I wouldn't mind something happening with my back boobs – they hang over the chair like a cape."

Will Young: "I look bigger than I used to, but I feel like a man, so I quite like it."