Celebrities have spots, too. Sarah Butters, 14, made this discovery when she and her Year 9 classmates at Attleborough high, in Norfolk, piloted an image awareness programme for schools.

The 80-minute workshop highlights the spotty, greasy, cellulite-laden reality behind slick celebrity photographs. It includes a DVD film, which transforms two pupils into images of supermodel-style perfection.

“I used to put myself down, and think I’m not that pretty,” Sarah said.

“But now I think celebrities are probably just the same. There’s nothing to stop me becoming a celebrity one day.”

Resources for the scheme are to be published on the internet next week alongside a survey that examines pupils’ attitudes to their bodies.

Teenagers from 10 countries were questioned.

British pupils betrayed particularly low self-esteem, second only to their Japanese counterparts. Susie Orbach, visiting professor at the London School of Economics and psychotherapist to the late Diana, Princess of Wales, conducted the survey with Nancy Etcoff, at Harvard university.

“This is a public health emergency,” she said. “It is a kind of body terrorism, and it is just as threatening as global terrorism. It’s like gravity - it is all-pervasive but people don’t even realise it’s affecting them.”

Professor Orbach also questioned 250 British teachers, of whom 97 per cent said their pupils worry about the way they look.

More than three-quarters said unattainable role models in the fashion and beauty industries were to blame for low self-esteem among girls; 60 per cent said responsibility lies with the images of celebrity perfection in the media, while 30 per cent blamed the promotion of plastic surgery and extreme makeovers.

Laura Cowan, assistant head at Attleborough, agreed with the findings.

“Teenagers’ perception is that if you see a picture in a magazine, then that’s how the person looks in real life,” she said.

“They would almost rather see themselves negatively than positively. Often their mum or dad is the only person who says nice things to them. Even the bright or attractive ones don’t perceive themselves that way.”

The survey acknowledged the power of peer pressure: 77 per cent of teachers questioned said teenage girls felt the need to look like other girls, while 34 per cent said they wanted to impress their male peers.

Ms Cowan hopes the Bodytalk scheme, sponsored by the soap manufacturer Dove, will tackle this issue. At the end of the lesson, participants turn to a friend and compliment them.

Sarah Butters was praised for her ability to cheer up her friends.

“When you’re with your friends, you don’t say things like that,” she said.

“But maybe we should. It made me feel a lot happier.”

Boys are also invited to take part in the workshop. Adam Greenwood, 14, believes he can often be as image-conscious as his female classmates.

“Boys are really quite obsessed with themselves,” he said. “They go down the gym to make themselves look better for girls. We’re all trying to get a girlfriend. But if somebody loves me, I hope they’ll ask me out whatever I look like.”

His twin brother, Jamie, has also taken away firm lessons from the workshop. “Photographs can play tricks,” he said. “So you should never judge a book by its cover. But I still want a girlfriend who looks like a celebrity.”

www.campaignforrealbeauty.co.uk

* adi.bloom@tes.co.uk

MODEL EXAMPLES

Dimitri Leonidas grins a typical teenage grin: unrestrained, toothy, and framed by spots. Soon, he reappears pouting moodily, his face porcelain white, hair transformed from a sandy crop to a shoulder-length mass of black. Under a coat of mascara, he is all huge eyes and blanked-out features.

He is one of the two pupils transformed into a supermodel in a DVD distributed as part of the new Bodytalk scheme. The film highlights the artificiality of the fashion industry, so Dimitri morphs from 14-year-old schoolboy into pouting goth and pose-striking indie-kid.

Katie Naughten, 14, is given freckles and new eye-colour to match a denim cowgirl outfit. Assistants wipe her teeth free of lipstick, and massage creams into her legs. She smiles from beneath a shock of backcombed hair with all the winsomeness of a pop star.

But there is no beast-into-beauty magic here: the DVD undermines its own point by choosing two naturally attractive models. The point might have been better made had their smiles been less perfect to begin with.

Dimitri’s spots, which are digitally removed to make a point, do not reappear later. Even Bodytalk, it seems, is not immune to the pressures of expectation and image.