Colette Douglas Home: I ran a designer dress shop for a day last year when the owner was away during her summer sale. I thought it would be fun. I was wrong. By the end of the day I felt profoundly sad.

I ran a designer dress shop for a day last year when the owner was away during her summer sale. I thought it would be fun. I was wrong. By the end of the day I felt profoundly sad.

My first customer was dark with a gamine figure. She tried on a coat which was tight as a sausage skin on me but on her delicate frame it hung just the way the designer had planned. I was silently admiring how good she looked when she said something like: "I'm so horribly thin, does it look scruffy?"

I was taken aback. "You look wonderful in it," I told her, adding quickly that I was not an employee so wasn't flattering her to make a sale. Bolstered by my enthusiasm, she tried on several other outfits and bought them. I had the impression it was a very long time since anyone had told her how pretty she was.

Next a small, curvy blonde took some dresses into the fitting room. "I have no neck," she told me, when she stepped shyly from behind the curtain, "and my waist is too thick".

And so it went on. Every single woman who emerged from the changing room to look in the mirror apologised for her body. They were either too bosomy, too hippy, too flat-chested or had too big a tummy. Their legs were too short or, when they were long, their waists were too high. Not one of them was comfortable with the way she looked. It was as if the mirror was one of those distorting ones from a fun fair. It wasn't, of course. It was their low self-esteem talking.

I remember one who tried on a stunning silk frock with the price slashed. Even she could see how good she looked. It was reflected in the sinuous way she moved in it. Then she put it back on the hanger, climbed into her dull old jeans and said: "I'd never be able to carry it off."

By the time I shut up shop for the night I could have wept. I felt invaded by the incipient unhappiness of all these women. I locked the door convinced I should open a therapy centre next door.

The pretty singer Lily Allen recently displayed the same syndrome when she wrote in her blog: "I used to pride myself on being strong minded and not being some stupid girl obsessed with the way I look. I felt like it didn't matter if I was a bit chubby cause I'm not a model, I'm a singer. I'm afraid I am not strong and have fallen victim to the evil machine. I write to you in a sea of tears from my hotel bed in Seattle. I have spent the past hour researching gastric bypass surgery, and laser liposuction."

Happily the world rushed to reassure her. But does any woman feel good about herself? Not according to the owner of the shop I managed. "It's like that every day," she said.

A French woman told me about her theory. She thinks British women apologise for existing because they are unappreciated. "In Paris," she said, "men on the street will catch your eye as if to say, If only ' It doesn't matter if you are 24 or 64. Here, men look through you."

I can't believe modern women measure their worth according to how attractive men find them. If they did they would be easily reassured. I had an unusual insight into what appeals to men at the most basic level when Edinburgh's saunas were licensed. I was writing about what was effectively the legalisation of prostitution and found myself invited into one of the saunas to meet the sex workers.

I didn't know I had an expectation of what these "high-class hookers" would look like until they didn't match up to it. There was one slender blonde, which I suppose was what I had in mind. There was also a butch young woman with her head shaved, one who was decidedly pear shaped and another who was as round and as soft as a feather-down pillow. To cater to all tastes, the owner had to provide all shapes and sizes.

It is the acknowledgement of that variety of beauty that women have lost. Instead of celebrating our differences we have in our minds a cardboard cut out of Kylie or Kate Moss into which we strive to fit - with as little chance of success as the ugly sisters had with the glass slipper.

We don't have a diet book each, we have a dozen. We have unused gym memberships and exercise bicycles and crunch machines with dust on them. With summer coming, instead of relishing the prospect of plunging into the sea, we cringe at the thought of the swimsuit.

It isn't about being attractive to men or competing with other women. It's about not being good enough. It's about measuring our bodies against flawless images that confront us day in and day out from television, newspapers and magazines. The message is that there is only one form of female beauty and, fools that we are, we buy into it then castigate ourselves for every ounce and inch of difference between how we are and how we think we should be.

Men don't torture themselves that way - at least not yet. They may wish to be a hint taller or a tad lighter but they don't lose sleep over it. And if they find in a clothes shop that there isn't a suit to fit, they have one adjusted. They should relish their peace of mind, for change is on the way. There is a new advertisement in the papers and - life size - in the stores. It depicts a bronzed young man lounging in white swimming trunks, gazing out at the women of the world through cobalt blue, dark fringed eyes. He is gorgeous.

In another advertisement the same company has a group of five or six Adonises standing around in their underwear, six-packs on show. It is the beginning of a growing trend. There's a television ad for men's face cream. The voice-over says: "What you see as laughter lines, she sees as wrinkles." Then, having created an anxiety, it offers a cream as the solution. It is basic sales strategy and it works.

The statistics speak for themselves. Already, one-third of shoppers on cosmetic web sites are men, and sales are rising. Men's clothes stores and gyms are being targeted as sales points. It is big business. The South American market alone is expected to be worth $6.7bn by 2015.

I say buyers beware. It seems harmless to see handsome, scantily-clad men, increasingly appearing in advertisements. It seemed every bit as harmless to see women that way when I was 20. I didn't see that their unattainable look was calculated to work on my insecurities but I can see the manipulation now that men are the target. Slowly, cumulatively those images of young, slender women have infiltrated the female psyche to its detriment. Men should resist having the same misery visited on them.

I urge them to sidestep the trap; to be aware of the sales techniques and to dismiss the message. The truth is that women see men's laughter lines as laughter lines. The truth is that we can look and mentally whistle at the pin up on the poster but we don't compare him with the real man in our life. The sadness is that women do compare themselves to the icons used by the beauty industry - and no cream or cosmetic is worth the price they're paying.