Jemima Lewis: Why change your body shape to suit a man?

With a pair of silicon footballs sewn into her chest, she will tip over into pure porn star

A family friend is having her breasts enlarged, and I am quivering with disapproval. She is only 24 - barely more than a child in my eyes - and quite pulchritudinous enough. With her long, supple body, white-gold hair and eyes of baby blue, she looks like a walking sex fantasy as it is. With a pair of silicon footballs sewn into her chest, she will tip over into pure porn star.

Moreover, as Dolly Parton once observed, it costs a lot to look that cheap. My friend is an air hostess, earning a very modest wage. She still lives with her parents, on the grounds that she is too poor to move out. Yet she has saved up £4,000 for a project of pure vanity.

How can it be that any modern woman should consider the size of her breasts more important than her ability to put a roof over her own head? I am only 10 years older than this woman, but a generational chasm has opened up between us. The mildly feminist notions with which I grew up - that women should try to rise above their insecurities; that men should love us for our personalities, not our secondary sexual characteristics - are nothing but empty platitudes to her.

She thinks it hilariously optimistic to argue, as I have tried, that men don't really care about breast size; or that some might actually prefer small, apple-y ones. "Everyone has their tits done these days," she says. "You look like a freak if you don't."

This is an exaggeration - but it points to a broader truth. The first time I saw a pair of silicon breasts was a decade ago, in a swimming pool in France. They were weirdly buoyant; which is how, after much whispered debate, my sister and I deduced that they were fake.

We were scandalised: first, that anyone would pay good money for such ludicrous baubles; and second, that they should be so unembarrassed by these symbols of their own vanity.

No one would be scandalised now. We see fake breasts everywhere: on television, in pop videos, in newspapers and gossipy magazines. The pornographic body shape, as perfected by Jordan, has moved into the mainstream; and the internet has made porn itself available to even the callowest youth. This is bound to change the way that men see women - and that women see themselves through men's eyes.

Just as the Victorian art critic John Ruskin was aghast to discover that real women were not, like the classical nude, smooth and hairless between their legs, so the modern lad - his sexual tastes formed by a diet of online porn - might be disappointed by real breasts. That, at least, is my friend's fear - and perhaps she has a point.

Two months ago, the lads' magazine Zoo ran a competition in which readers were given the chance to "bag a new set of rib lamps" for their girlfriends. All they had to do was send in a picture of their partner's inadequate breasts and the name of the celebrity pair they would like substituted, and a surgeon would take care of the rest. As well as getting some "new playthings", the lucky winner - yet to be announced - will get £1,000 and the chance to "show just how much they love their girlfriend". In my day, a box of Terry's All Gold would have sufficed.

The British Association of Aesthetic Plastic Surgeons (BAAPS) last week condemned this competition, which it said trivialised the medical profession and violated ethical codes of practice. But Zoo is unrepentant. "Having a boob job is a lifestyle choice made by thousands of women each year," said a spokesman.

Statistically speaking, this is correct: 75,000 cosmetic procedures were carried out in Britain in 2003 (the third highest per-capita rate in the world after America and Brazil), of which boob jobs were the most popular. Popularity, however, is no proof of virtue. All these figures really show us is that the women of Britain are frighteningly insecure. In a recent survey, two thirds said they hated their bodies so much they would like to go under the knife. But surgery cannot cure the condition of physical self-loathing: on the contrary, it spreads the plague by raising everyone's standard of beauty to an unnatural, homogenised ideal.

If the media are guilty of ratcheting up our standards - and hence our insecurities - plastic surgeons are guilty of cashing in. Theoretically, they assess each patient's psychological state to filter out those whose problems are more mental than physical. How, then, did my friend get an appointment for surgery?

There is nothing wrong with her body; her ailment is purely philosophical. She comes from a culture that cannot distinguish between vanity and self-improvement; that panders to the basest instincts of the silliest men, and calls it "feeling better about yourself". A conscientious doctor would have sent her home with a copy of the Female Eunuch and a flea in her ear.