I survey the sea of faces before me - an average-sized, co- educational Year 10, comprised of 160 teenagers. Some students are leaning forward eagerly in their seats, while a handful are attempting to look totally unbothered and a few are trying to plug in iPod headphones without me noticing. Then their head of year says the magic words: “Natasha has been on the telly. With Gok Wan.” Suddenly every student is alert, all attempts at indifference abandoned.

I have one hour to convey the message that inspired my business, Gossip School; just one hour to emphasise the importance of self-esteem, to give these young people the tools to recognise negative messages from the media and to convince them that it is OK to be themselves, however they look.

Statistically, 15 of them will have self-harmed at some point during the past week, 16 are either suffering from or will develop an eating disorder before they are 25, and 55 will have been verbally or physically bullied by their peers.

It is impossible to tell who among my audience is enduring the issues described above. I cannot assume that they will be female (according to the charity Men Get Eating Disorders Too, with which I work closely, diagnoses of male eating disorders have increased by 66 per cent in the past decade). All the social mores have changed. Low self-esteem knows no barriers: it is now the remit not only of the class clown and the nerd, but also the sports captain and the most popular girl in school.

Statistics tell me that 70 per cent of the young women before me, and almost half of the young men, are dissatisfied with their appearance. But what was once common-or-garden teenage angst now has a new and terrifying face, exacerbated by the internet, airbrushing, aggressive marketing campaigns, cheap diet drugs, cosmetic surgery, broken homes and exam stress. Teenagers often seek solutions to these pressures in the imagined control they feel when they develop an eating disorder or self-harm, and their unhappiness can spiral out of control.

I began teaching self-esteem classes in 2008, speaking to hundreds of teenagers to develop my lesson. Self-esteem education is now my full-time job. I have worked with almost 10,000 teenagers aged 13-18 in schools, colleges and universities throughout the UK. This year, I am bringing in other presenters to reach an even wider audience and am developing a lesson for younger pupils, aged 11 and over.

My lesson begins with my own story. Aged 17, I was a straight-A student, deputy head girl and a champion Oxford Union debater, excited by the prospect of university and utterly convinced that one day I would be prime minister. I wore a uniform of Marks and Spencer navy bootleg trousers and did not wear make-up or have any interest in fashion.

Eight years later, having embarked on an ill-fated modelling career, I was bulimic, unemployed, pound;10,000 in debt and suffering from depression. I had 24-inch hair extensions and a fake tan, and would pore endlessly over glossy magazines. I also had a hole in the roof of my mouth (eroded by vomit), had been hospitalised twice with dehydration and had been rendered a shadow of my former self by bulimia, which was robbing me of my potential.

I have now been in recovery for four years. My experience seems to make me somebody teenagers can relate to. I retain some fondness for fashion and glamour, but it is not all-encompassing. My lesson’s core message is that, however you look or are, you can only be the best version of yourself, which is so much better than chasing some arbitrary beauty paradigm.

I encourage students to identify and question their negative beliefs about themselves. The commonest of these are “I’m ugly”, “I’ll never pass my exams” and “I’m not liked”. By the end of the class, I hope I have been able to give them a fresh perspective - one that will put them on the road to self-acceptance and to knowing they can do anything they set their minds to.

I then help students to take an incisive look at the media, specifically advertising. A study carried out by the Centre for Appearance Research last year showed that an overwhelming majority of adults feel mildly depressed after being exposed to airbrushed images - and the young minds of my students are even more impressionable. I cannot reverse the thousands of harmful subliminal messages to which they have been exposed, but I can give them the tools to recognise when they are being manipulated.

At the end of the hour, I am always surprised by the variety in shape, size, race and level of outer “confidence” of the students who approach me and confess that my lesson has touched a personal chord.

I recently returned to the school where, two years ago, I taught Jesika Foulkes, now 17, who found the courage to seek help for her eating disorder after attending my class. She told me: “My school work suffered when I was obsessing over how I looked. I also had no energy and drive to actually do it. Your class made me realise that I didn’t want to be that way any more.” She is now in recovery, studying for her A levels.

We are living in uncertain times when it comes to emotional education. The government has removed the need for PSHE to be mandatory, yet Ofsted would be highly critical of any school or college that ignored the Every Child Matters policy. But while education secretary Michael Gove champions “traditional” academia and dismisses whole sets of vocational qualifications, students also need their mental and emotional health to be supported and nourished.

Anyone inclined to disagree should take a look at Maslow’s hierarchy of needs, which states that every individual must have a foundation of self- esteem before they can focus on more intellectual matters. However excellent a school’s teaching and however bright the student, both will fall short of fulfilling their potential without the right emotional guidance from the right people.

Natasha Devon is co-director of the Body Gossip campaign, the founder of Gossip School (www.bodygossip.orggossipschool), which has just won a business award, and a body image expert for BBC radio. The first two schools to email Natasha will each win a free Body Gossip course. natasha@bodygossip.org

HOW MY BODY WORKS

Francine Gerstein, a family and cosmetic medicine specialist, journalist Liza Fromer and illustrator Joe Weissmann have teamed up to create the Body Works book series (published by Tundra Books).

Even before they start school, children can be self-conscious about how they look or feel. The aim of these books, targeted at key stage 2 pupils, is to introduce them to the aches, pains and noises their bodies make, helping them to understand how they function while developing self- esteem.

Filled with facts, lively descriptions and beautiful drawings, each book encourages pupils to feel at ease with their bodies.

WHAT ELSE?

Key stage 1: Food for thought

Understanding diet is the first step to a healthy lifestyle. Teach pupils why certain foods are good for them with QCDA_Resources’ lesson plan.

Key stage 2: Beauty on the box

Television, film and advertising inform our ideas of beauty from a young age. Make pupils media-savvy with Media Smart’s self-esteem pack.

Key stage 3: In it together

By playing agony aunt to their peers in pennymcb’s lesson, pupils will learn that they are not alone.

Key stage 4: What is `normal’?

Why do we obsess about being “perfect” or “normal”? What do these words even mean? Youthhealthtalk’s activities will get students thinking for themselves.

Find all links and resources at www.tes.co.ukresources030.