Why should my bum look big in this?

Because high fashion is designed only for boyish bottoms and flat chests. Laura Tennant is fed up

September's Vogue was even fatter, shinier and heavier than usual and, once again, I didn't have the moral fibre to resist heaving its 400 pages, headily scented with the superior solvent of fresh magazine, onto my lap. But glossies are like the magical Turkish Delight in The Lion, The Witch And The Wardrobe. The more you have, the more you want and the sicker you feel. Why women should want to look at pictures of other, more beautiful women has long been a mystery. But we're perverse creatures and maybe we get a weird masochistic thrill from feeling angsty and insecure.

At least, that was what looking at magazines used to feel like. And, in defence of them, editors would explain that they were inspirational. You would never look like the girl in the picture or be able to afford the coat she was wearing, but you could aspire. Chanting your feminine mantra (must try harder, must try harder), you could save your pennies and get a high-street version, you could go on another diet, or you could buy the designer label mascara, a sort of holy relic to bring you closer to the glossy state of grace. Hopeless aspiration is not terribly comfortable, but what was represented in the fashion magazines was at least glamorous and elegant.

But in the past five years, something peculiar has happened. I flick through Vogue and I don't want to look like the girls in the pictures anymore. In the first place, I don't want to be so skinny that I have concave thighs and no breasts. I don't think it's sexy to sit in that curious collapsed position - spidery arms and legs stuck out at awkward angles - that stylists and photographers are so fond of. I'm also irritated by the "I'm not very bright and I've recently suffered severe trauma" expression models are asked to affect. Also, I don't want to wear Gucci jersey dresses with alarming holes down the side, out of which bosoms are likely to slip, transparent chiffon dresses, underwear as outerwear, precipitously high stilettoes with ankles socks, school uniform, skin- tight leather or hot pants, for the simple reason that I am not a complete slapper.

For autumn, I notice, it is suggested that we wear the Michael Kors slitted micro-mini with high heels and no tights. "You have to watch what underwear you wear... a sense of decency is essential," advises Mariuccia Mandelli of Krizia helpfully. Hello? Under what circumstances would any girl want to flash her knickers, however decent those knickers might be? As a prelude to sex, maybe. (On the subject of sex, doesn't it infuriate you the way glossies have sexualised fashion and beauty to the point where naked breasts and bottoms are de rigueur? What is this, a women's magazine or soft porn?)

If we're not being "inspired" to wear clothing which doesn't clothe, we are being offered designs that do the female form a mischief. The ubiquitous flat-fronted, hipster, bootcut trouser, for example. If you're over a size 10 and under 5ft 8in, this shape of trouser is so hideously unflattering as to add a good 12lbs to its hapless wearer. Then there are Prada's below- the-knee, A-line skirts, Helmut Lang bin-bag dresses, anything long, enveloping and hessian, and designs that would look cute only on small boys. They have all been conceived with a callous disregard for what suits your average, size 14, 5ft 5in woman.

Planet fashion has always been pretty strange. But in recent times it seems to have come crazily uncoupled from its function. Architects, however recherche, are constrained by the fact that their buildings must be liveable in, just as furniture-makers, however avant garde, must design chairs people can sit on. Yet, that strange and powerful matrix of fashion designers, editors, stylists and photographers seem to have lost sight of the fact that clothes are intended to be worn by real people and that good design adorns, flatters and enhances. It works with the body, not against it. Bosoms and bottoms aren't encumbrances without which clothes would hang better, they are what a woman's shape is. But what real women might look attractive in and find wearable and comfortable long since ceased to interest fashion. So much so that even protesting about it feels mumsy and old-fashioned, special pleading for those of us unfortunate enough to be neither enormously fat nor enormously thin, just normal.

Sensing an unplugged gap, BBC2 has commissioned a new series called Looking Good. "There are only three questions grown-up women want to know about clothes," presenter Lowri Turner points out. "'Does it make me look fat? Do you have it in a size 14? And can I put it in the washing machine?'" These questions may seem pretty remote from Alexander McQueen's latest collection for Givenchy, or the shooting of Vogue's big stories for Spring 1998. But until fashion reforges the link between form and function, design will loop the same self-serving, self-referential loop. And I will continue my search for a pair of trousers that don't make me look like a baby elephant.

Looking Good, 2 September, BBC2.