'Mummy, will I get fat?'

One four-letter word has always been strictly banned in our house: D.I.E.T. After I interviewed the mother of an anorexic six-year-old who wanted to be slim "like the models in magazines", I made sure I never so much as uttered it in the hearing of my two young daughters. If other adults brought up their own diet regimes within their earshot, I discreetly changed the subject in case they soaked up the idea that it's a woman's lot to starve herself.

Because I wanted Lily and Clio to have a real childhood, I also monitored what they watched on TV, what websites they visited and what magazines were left around our home. So it came as a shock when one day my younger girl, Clio, who at five was barely old enough to read, picked out the word "fat" on the ingredients list on her yoghurt and announced: "I'm not eating this – I'll get chubby." Lily, too, had got the message. I found out "fat" has become the most feared insult at primary school when, after a playground squabble, she put herself on a diet, aged seven.

Like many other parents, I was already aware something was going badly wrong for our daughters because of the way girls are growing up too fast.

In study after study in the Western world, the issue had been identified and analysed in great depth. Now my experiences with my daughters had taught me that no matter how many towels I pressed around the doorframes of our home, sexualisation was like a gas that seeps through the cracks.

At a time when they should have been completely at ease with themselves, they were being fast-tracked through childhood. Before they had become women, they were already comparing themselves to stifling stereotypes of what women should look like.

Yet for all the extensive research and the moves towards Government regulation, as a parenting author I found little that told parents how to protect their girls. Perhaps as a result, when I interviewed parents for my new book Where Has My Little Girl Gone? I found a real sense of fear and powerlessness.

I discovered families felt drowned out by advertisers, marketers, the internet and negative peer pressure. As soon as the situation had slipped out of their control, many had taken the route of weary surrender. "There's nothing we can do," was a common refrain. But it's far too soon and much too dangerous to fall into a state of paralysis. Ultim-ately, the mental health – the happiness – of our children is at stake.

One in 10 UK children suffers from some form of mental illness, according to the Mental Health Foundation – and what makes girls most unhappy is how they look. It's heartbreaking that little girls are already judging themselves as losers in the beauty contest of life.

While it's true we can't shield our children, there is no reason why we should sit on the sidelines. By helping girls question the pressures placed on them, we

can help them work out for themselves what is good and bad for them and fend those influences off. By talking about and explaining what is happening around your daughter, you can help to shelter her against the erosion of her self-worth. In the two minutes you take to show her how a photo of an ultra-skinny model has been airbrushed, you have taught her not to hold herself up against an ideal she can never live up to.

If we can also create a strong core of self-belief during our girls' formative years, they will be more able to resist pressures to reduce themselves to the sum of their physical features. By opening up channels of communication we also stand the best chance of staying closer to them when the going really gets tough.

But we also need to organise our own attitudes and ideas so the messages we send our girls are healthy, clear and consistent. After all, if we were born during or after the 1960s, we were the first generation to grow up in a world dominated by TV. As children, we soon picked up that for a woman, being thin and beautiful equalled sexy and successful. Our generation has seen the rise of reality TV stars, WAGs and manufactured girl bands who have collectively sent the message that you can be rich and famous without talent. Have we also unconsciously signed up to the idea that females need to look a certain way to get on in life?

I spent a day at one of London's biggest plastic surgery clinics and found that more than half the patients were girls in their late teens and early twenties whose parents were paying for their liposuctions, nose and boob jobs. Like X Factor mentors, they believed that surgical procedures were what their girls needed for "confidence", that a perfect appearance is what a modern girl needs to get on in life.

Painful though it may be to admit, the first lessons girls get about their appearance – and ultimately self-worth – come from us, their parents. Children begin to recognise themselves in the mirror at about two years old. Within a few years, girls (but not boys) barely old enough to know their alphabet, don't like what they see. Half of girls between three and six worry about being fat, according to research published in the British Journal of Developmental Psychology.

As they see us skip meals, obsess about weight and criticise our bodies, girls learn at their mothers' knees that body size is a powerful issue that can make us feel like successes or failures. As Deanne Jade, founder of the National Centre for Eating Disorders, says: "Even if you think you are modelling good behaviour by telling your daughter you are going to the gym to get healthy, not thin, it can create the anxiety in a child that it's the only way to be healthy... Everything we say sends a message which can be much louder to the ears of a child." Then, as soon as they step outside the front door or switch on the TV, those messages are reinforced. When I counted the images of women Lily, now nine, sees on her half-hour bus trip home from school, it added up to more than 20. Almost all were size 6 to 10, partially dressed or in underwear. On average the females wore about 20 to 50 per cent less clothing than men. No wonder Clio asked me last year: "Why are boobs so important?"

Some parents insist every generation is shocked by what the younger generation does. They argue little girls have always wanted to look older and try on their mothers' high heels and lipsticks and it didn't do them any harm. That may be true, but while we may have looked a couple of years older than we were at 12, did we really look 18? And the pornography we may have seen – after a lot of subterfuge – would have been the softcore variety, not the hardcore kind that is now the only material you see on the web.

Now we face a perfect storm in which celebrity, porn culture and consumerism have come together into a whirlwind that parents feel unable – sometimes reluctant – to withstand.

By our standing by and doing nothing, our daughters have had the hard-won freedom to grow into whom and what they want to be taken from them. They have learned they will be seen as successes only if they fit into a very narrow stereotype of attractiveness and success. Instead of enjoying a carefree childhood, they feel they have no choice but to spend it working out a way to fit into this hierarchy. As Dr Linda Papadopoulos, author of the Home Office Review on Sexualisation, told me: "Research shows that when a little girl feels that being sexy is the reason she is valued, she is more likely to spent more time and energy on what she looks like – instead of other areas of her life, like education."

Porn and prostitution have become mainstream in our culture, even aspirational. More than a million people were glued to TV's Secret Diary of a Call Girl this spring, in which Billie Piper played a high-class sex worker with an enviable lifestyle of walk-in wardrobes packed with Manolo Blahnik shoes. Those aspirations cross all sections of society. I came across a 16- year-old at a top public school who was so proud of the term "slut" that she had it in giant letters as her phone screensaver.

In the past, magazines and TV shows were careful not to step over the line as they feared a parental backlash. But because we have worried it would look "uncool", "right-wing", or "anti-free speech", we've said and done nothing for so long that few dare speak up.

In years to come, I hope we will look back at this era in the same way we once viewed children being sent down mines and up chimneys. Just as Victorian labour practices robbed those youngsters of their childhoods, our X-rated culture is robbing our daughters of theirs.

One incontrovertible fact shows it's gone too far. Such is the sex industry's fascination with corrupting innocence, that adult women in porn shave off their pubic hair to look like children. That's now the fashion for most women I know – illustrating how acceptable it has become to remove the boundaries between adulthood and childhood.

Deep down, I believe society still knows children should be protected. It's up to us as parents to pull together and use our voices to remind marketers, legislators and TV channel bosses.

I support the Government's latest reviews looking at how to curb the sexualisation of children and stamp out the easy access to free pornography.

But as our children's foremost role models, the most important thing we can do is reclaim our positions as first gatekeepers in their lives and turn the tide back so our daughters can be children, not trainee sex objects.

We should aim to make it as tasteless to throw makeover parties for little girls as it has become to buy them cigarette-shaped sweets and toy guns.

'Where Has My Little Girl Gone? How To Protect Your Daughter From Growing Up Too Soon' by Tanith Carey is published by Lion Hudson on 20 May at £7.99

Too much too young: the pressures girls face

* Twice as many British girls as boys suffer "teenage angst". As many as 900,000 girls describe themselves as "unhappy and depressed".

* 24 per cent of girls aged 16 to 21 would consider cosmetic surgery, while 12 per cent of those aged 11 to 16 would consider a gastric band.

* 76 per cent of UK girls aged 15–17 say it is hard to feel attractive in the face of today's beauty ideals, compared with a global average of 58 per cent.

* 27 per cent of 15-17s say the media was one of the earliest influences on their body image.

* 70 per cent of teachers say celebrity culture affects pupils' aspirations.

* Around 1.1 million people in Britain have been affected by eating disorders, mostly the 14-25 age group.

* Girls aged 13-19 account for half of all bulimia and anorexia cases.

* People aged 18-24 are most in favour of regulating porn. Four in ten say it damages relationships.

* One in four college students who recall first viewing pornography as children say they initially felt "disgust, shock or surprise".