Health chiefs fear the childhood obesity campaign is backfiring. And to listen to these teenagers, they have every reason to

Steph Ashcroft and her friends from Year 9 at Warden Park Secondary School near Haywards Heath in West Sussex, have more important things to worry about than obesity. Such as music, boys and pocket money.

Steph Ashcroft and her friends from Year 9 at Warden Park Secondary School near Haywards Heath in West Sussex, have more important things to worry about than obesity. Such as music, boys and pocket money.

"We've touched on healthy food at school, but not in any great detail," said 12-year-old Steph. "Most of us are healthy anyway. I eat a lot, but I don't get fat because I do karate. It's people up in the north who aren't healthy; big, fat, flabby people. They're the problem."

Her reaction is exactly what the Government's official food advisers expect - and what they fear, according to an internal Food Standards Agency report seen by The Independent on Sunday.

It warns that the drive to alert teenagers to the dangers of obesity is backfiring, because the "healthy eating" message is boring and negative.

Instead of switching to healthier low-fat and less sugary foods, teenagers are starting to "screen out" government warnings about the risks of fast foods, sweets and ready meals.

Young people often see healthy eating as an issue for fat and obese teenagers - not themselves, the report says. This is leading to "compassion wear-out", increasing the risks that young people will reject calls to eat healthier food.

They are often cynical about some products' claims to be healthy. One 13-year-old girl interviewed for the study denounced Sunny Delight. She said the drink was supposed to be full of vitamins and all fruit, but was actually additive-laden. "You can't believe any of the stuff they say on packs," she said.

The agency is using the report's findings in a series of new initiatives to tackle Britain's rapidly growing obesity problem, which will culminate in a government White Paper on health, due out next month.

Young people are seen as a crucial target audience for this campaign. Recent figures suggest more than one-fifth of all children are overweight or obese - partly because of a sharp growth in the use of fast foods, and a steep drop in activity by teenagers.

The latest health studies warned that rising obesity is leading to a surge in cases of type 2 diabetes in younger adults - a form of the disease previously confined to older people. Obesity in children hastripled over the past 20 years.

Stark warnings, the FSA report suggests, are having little impact on teenagers' eating habits. They are more influenced by foods that are seen as cool, attractive or likely to make them physically fit.

The report's authors interviewed children aged 11 to 15 in London and Birmingham, and found that girls are most concerned about being slim, sexy, happy and fit. Boys also like being fit, as well as having toned muscles and getting energy from food.

Appeals to eat healthy meals are only likely to succeed if they are linked to sports stars, celebrities or fashion trends - making the link between looking good and eating healthily.

This finding will be used by the FSA to counter calls for a total ban on promoting unhealthy foods to children - a measure the Government could endorse in next month's White Paper. The agency believes advertising with celebrities such as David Beckham, who promotes Pepsi, or Gary Lineker, who sells Walkers crisps, can be used to subtly promote healthier foods.

Dr David Haslam, a GP with the National Obesity Forum, said official campaigns had to be less squeamish about appealing to a teenager's interest in looking good. "The way to get the message across is not to say: 'This is the way you will end up when you're 50," he said. "It's about 'Look how good this girl looks, this is how to do it.'"

At Haywards Heath, the girls say their school has tried healthier alternatives in the canteen, but this has failed to whet their appetite.

"They say they're giving us the healthy option, but it's too expensive and doesn't taste as nice," says Sarah O'Sullivan, 13. Her classmate Georgia Canagon, 13, had a different concern. "I don't want to grow up to be really chubby, because sometimes if you're fat you have to pay more to travel," she said. "If you don't fit into an economy-class seat, you might have to go in business class."

Steph's friend Jessi Rivera, 13, was more reflective. "Obesity is being blobby and horrible, so I never want to be obese," she said. "But I'm not overly worried about the future, because I like to eat. If I'm going to die of a heart problem, I'd rather die happy."

"Teachers say we should try to eat healthily, but they have revolting meals at lunchtime," she added. Steph singled out her father. "My dad would say that salad isn't proper food," she grinned. "His idea of a normal meal is two big portions of spaghetti bolognaise."