When you look in the mirror, how good do you feel? Monday sees a Commons hearing that some will mock as a waste of time, but that millions of women, and many men, ought to applaud. It's the all-party group on body confidence, and it will be interviewing witnesses from the media and advertising industries.

The campaign for body confidence was kicked off by the Central YMCA, the health and fitness charity, which was surprised and disturbed by how much the issue affects young people. Its chief executive, Rosi Prescott, says "we can start to see this taking young people over" as ever thinner celebrities are featured in magazines while digitally enhanced images of perfect bodies are all over the internet.

Now MPs are starting to take an interest and are listening to the horrifying facts and figures. At the sharp end, there are more than a million people, mainly teenagers or young people in their early 20s, with an eating disorder. And let's not forget the thousands of women who are victims of the cosmetic surgery boom, which includes the current breast implant scandal. If you think this isn't "political" or the job of MPs, you must have a very narrow idea of politics.

As Jo Swinson, the Lib Dem MP who chairs the MPs' committee says, dissatisfaction with one's body has never been higher: the pressure from the fashion industry and advertising means "low self-esteem, depression and eating disorders are all increasing". Half of all girls aged 14 have dieted and a third of 14-year-old boys. Isn't this weird? Creepy?

It's a quiet epidemic of kids taking laxatives to lose weight, young men taking steroids, girls throwing up or committing themselves to odd and dangerous restrictions in food. The lifelong effects are becoming clearer; they include wrecked careers and permanent ill-health.

The "commonsense" response that many older people will have – get over it, shake yourself down, just start to enjoy life – now looks dangerously naive. There is simply too big, noisy and powerful a commercial drive behind making people feel bad. Why? Because of the fortune to be made in making them feel just a little better again.

At the base of this industry are the drug companies that are pushing "wonder" cures and diets, tanning firms and heavily advertised cosmetic surgery specialists, as well as mainstream cosmetic firms. They all depend on the advertising and fashion firms that are selling an idealised, youth-obsessed beauty cult that is far beyond the reach of most real humans; and they in turn squirt glossy profits into the media spreading the cult.

Against all this, what chance does an impressionable, insecure 14-year-old have? Or for that matter an insecure man in his early 20s? For this is not a women-only problem. Though girls are still vastly more likely to suffer from anorexia or to go for cosmetic surgery, the growth of male anorexia in recent years is very striking. Endless appeals to the fashion gurus to rethink the models they use have received a cold-hearted brushoff. The death at 28 just over a year ago of the anorexic French model Isabelle Caro, who had bared herself to shock the fashion industry, ought to have produced a dramatic rethinking. Go and look at the images, if you can bear it, on the web. Isabelle said: "It is everything but beauty… I have psoriasis, a pigeon chest, the body of an elderly person.

There have been some advances, notably the ban on digitally altered body images in advertising, but battle has hardly been joined so far. We've become used to the idea that super-sized salaries have a disillusioning and depressive effect on normally paid people. Even the Tory-led coalition is interested in the "happiness agenda". How we feel about our bodies, comparing them with waif-children in magazines, the adolescent gamines and beardless urchins of the runways, is also about our general happiness and self-confidence.

So the question is, what can be done? The first thing is the proper, widely cast investigation the committee is doing: among Monday's witnesses will be companies such as L'Oreal, Boots, Unilever and Proctor & Gamble, as well as the publishers and editors of young people's magazines. An earlier hearing brought some electric evidence from Susie Orbach, psychotherapist and author of Fat is a Feminist Issue, when she confronted Weight Watchers over what is thought to be the most expensive (£15m) advert ever shown in the UK.

You can't legislate for what's in people's heads, nor should you try. I wouldn't like to see a new censorship. But if government can try to influence how much people drink, how much exercise people take and their eating habits, then it can certainly do more to help support people who are being made miserable merely by being ordinarily shaped. It could regulate the advertising and the practice of cosmetic surgery more closely. It could insist that commercial dieting plans carry independently monitored evidence of their effectiveness, or lack of it, just as we now expect calories and additives to be listed on food labelling.

Above all, though, simply by raising the issue and constantly talking about it, politicians and journalists can change the culture, or at least nudge it. This is, after all, how all campaigns start. Perhaps because it provides such lucrative advertising, the mainstream media has been ludicrously slow to ridicule and attack the skinny-model fashion houses and the snake-oil diet sellers. We have been far too polite, and po-faced; and as a result we have done our children a terrible disservice.

Twitter: @jackieashley