On Saturday afternoon at London's South Bank, the sun showed up and even more startlingly, so did over a thousand stark naked cyclists of all ages, all sizes and colours. They rode unselfconsciously, letting strangers behold their bums, boobs, knobs and muffs. A good number showed off with piercings and paint, flowers and vajazzle, bells and feathers. Bus drivers were apoplectic and fully veiled women leered through their small eye slits, their blushes unseen. The bikers were protesting against aggressive drivers, a worthy message shoved aside by erotic excitement and the infinitely various human forms one never sees in public. Without knowing it, the nude swarm cocked a snook at diktats about the body beautiful, and though brief, it felt liberating for gobsmacked spectators.

Then, like the sun, they were gone and billboards retook the space with their army of "perfect", thin, long- haired, wide-eyed, airbrushed women and George Clooney clones, as in the glossy magazines, glam TV shows, commercially oriented internet sites and newspapers. The images infect our eyes, pollute our hearts and disease our minds, but the industries responsible go on without having to account for any of the damage. The worst gambling bankers, quacks, food and drink purveyors, cigarette manufacturers even, are more answerable than the brokers who actively encourage self-loathing and profiteer by promising false cures. Though men are now in their sights their evil schemes mostly entrap females, from the first time a girl recognises herself in the mirror to the day an old woman dies. Researchers are finding that females of all ages have a distorted and negative view of their faces and bodies.

This week Tamara Rojo, the exquisite Spanish ballet dancer and newly appointed artistic director of English National Ballet, spoke out against anorexia among ballet dancers. Another laudable iconoclast is the editor of Vogue, Alexandra Shulman, who campaigns for wholesome and "real" female pictures. She is launching the Health Initiative to get her peers to consider how selling unattainable physical aspirations creates unhappiness and almost certainly increased levels of anorexia, bulimia and self harm. There may be deeper underlying reasons, but the merchandisers of popular culture trigger and feed the illnesses. (A landmark study in Fiji in the 90s found no anorexia or body anxieties before western TV arrived and then within three years, it all changed for the worse.)

Now here is the really sad news. The gorgeous, Adele, queen of song, on the cover of Vogue, would not let her body be included. How long before she goes the way of Sophie Dahl, Nigella Lawson, scores of others? We cannot blame them. Fame demands they must be thin and flawless. Let's turn to the Indian star Aishwarya Rai, once described by Julia Roberts as the most beautiful woman in the world. Rai had a baby six months back and hasn't done a Victoria Beckham, dropping down to an adolescent size, which trendy young mums must strive to do. The attacks on her border on sadism. It never used to happen in India, now it does. Across the globe, professional women, bright young girls, artists and even magazine hacks cannot deal with their self-hatred except through self-punishment. Hillary Clinton has been roundly abused this month for being "overweight", not wearing full mask make-up and an immaculate hairdo. Never mind Syria, woman, go on a diet.

The depiction and place of females in all societies has been determined by power and politics. Rarely have we been completely free to like ourselves and shape our lives. That historical imperative mutates, takes on disguises, but never yields, according to the American professor of psychiatry, Joel Yager: "Every society has a way of torturing its women, whether by binding their feet or sticking them into whalebone corsets. What contemporary American culture has come up with is designer jeans."

The extent of contemporary mass media brings new terrors, even more tyranny. The fact that women have dramatically improved life chances means people don't take seriously the internal chaos and insecurity dispersing through our gender. And there are the enemies within – female editors, businesswomen and TV high priestesses who, for professional and personal gain, coldly destroy girls and women. They use size zero models, force celebs to thin down, watch and humiliate the highest of achievers and together with their male plotters have created what academics call "normative discontent". Rates of young female depression have doubled in the last decade and now older women are being programmed to fall short of impossible ideals. Soon there will be coffin chic, post-death plastic surgery, experts judging how good we looked in the box.

Psychotherapist Susie Orbach has long fought the toxic cultural forces that make women hate their looks. I have never known her to be as apprehensive as she is today: "How did we get here?" she asks. The guilty will not hear the question. With so much cash and kudos why would they?

y.alibhai-brown@independent.co.uk