Generation excess: who is to blame for our fat children?

'Hungry? No, I'm not really. We've just had burger and chips for lunch, and pudding, but there's nothing much else to do at break time, so me and my friends all go over to the sweet machines. I get pocket money to spend at school so I usually have a Mars or a Twix, but some of the other girls have more money, so they get three chocolate bars and two bags of crisps each, and eat them all at once.

'Hungry? No, I'm not really. We've just had burger and chips for lunch, and pudding, but there's nothing much else to do at break time, so me and my friends all go over to the sweet machines. I get pocket money to spend at school so I usually have a Mars or a Twix, but some of the other girls have more money, so they get three chocolate bars and two bags of crisps each, and eat them all at once.

"After school we walk up from the bus stop together and call in at the corner shop to buy some chocolate to eat when we're watching TV at home."

Sally Harris is almost 12. She started secondary school in north London in September, and after years of packed lunches (with school rules allowing nothing more chocolatey than a Penguin biscuit), she was stunned to discover that when it comes to snacks, sweets and fizzy drinks, her new school is Liberty Hall. A lunch card not only allows her to buy a meal (choosing today from burger and chips, curry or a "healthy" option), but to queue up at break for a chocolate muffin. And if you've got the cash there's as much high-fat food as you can eat in the vending machines. After a term feeling thrilled at the new-found licence to snack, Sally is slowly realising that maybe it's not such a good thing after all, and has come to her own decision to cut out the muffin at least.

Like Sally, many of her pre-teen classmates are already overweight; some even obese, and because girls are far keener on hanging around than running around, there's little prospect of that changing. Weight-gain in children is becoming a serious problem in the UK. A million under-16s are overweight, twice as many six-year-olds are obese now than were 10 years ago, and 20 per cent of four-year-olds are overweight.

"Even by the age of nine an overweight child may have higher blood pressure and cholesterol levels than a child who isn't fat," explains Belinda Linden, cardiac nurse at the British Heart Foundation. The harsh facts are that a fat child is nearly seven times more likely than a slim child to become a fat adult, and simply being overweight significantly increases their chances of becoming diabetic, developing heart disease, gall bladder problems and some types of cancer. In addition to the numerous health concerns, obese children are likely to suffer psychological damage, bullying and self-image problems that are often carried through to adulthood. So why are children continuing to overeat, and why are their parents continuing to overfeed?

"Many health professionals assume that parents should bear most responsibility for bringing up a fat child," says Professor Jane Wardle, a clinical psychologist and co-founder of the charity Weight Concern. "But it's not that parents are wilfully lazy or bothering less; it's simply much easier to become fat than it was even 10 years ago. There's very little evidence that parents in families where children are overweight feed their children much differently from other parents."

Professor Wardle believes we are now living in an "obesogenic" environment where it has become normal to eat lots of high-fat food, spend hours watching TV and use the car instead of walking even short distances. "Fat children aren't simply lazy or greedy," she argues. "We adults need to take responsibility for shifting what's 'normal' to a healthier environment. We shouldn't be haranguing children about what they do and eat; instead we should work towards providing an environment where they get on with their lives, protected from junk foods and sedentary activities."

By the time they have reached secondary school, eating and lifestyle habits are hard to break, so it is far easier to tackle weight gain in children during their pre-school years, when parents have more control, or so they think. Valerie Rich was shocked when she took her three-year-old son Alex for a standard developmental check-up. "I discovered he'd risen to the very top of the weight chart appropriate for his age and height – at 102cm, he was 22 kilos," she recalls. "He's always been chunky but seeing his weight gain on paper made me feel a bit guilty. It was a wake-up call for me to look much more carefully at our family eating habits.

"I realised that although he's always liked his food, Alex had gradually become a pickier eater. The trouble started when he began going to birthday parties and discovered the delights of crisps and chocolate, which I'd carefully kept from him until then. He made such a fuss about eating that, to keep the peace, we were all having more snacky foods rather than proper meals."

Valerie also looked afresh at how much activity there was in Alex's routine. "We have to get in the car to go anywhere, and there's no outdoor play area in the nursery he goes to, so Alex doesn't get a lot of exercise," she says. "I don't want him to tip over into being too big, and I'm now conscious that I need to monitor the situation to prevent his weight becoming a problem. On the health visitor's advice I'm going to walk more, cut down Alex's milk and be firm about him eating decent meals."

It is easier now than ever to put on weight, and a fat child may not be unusual at school but that is no guarantee against their size making them the victim of bullying. Professor Wardle has shown that children are likely to identify a fat child as "lazy", "stupid", "mean", a "liar", and the least desirable of friends compared to thinner children. Thomas Saunders, 11, is 4ft 10ins and weighs eight and a half stones. He was made so miserable by classmates' taunts of "Fattie" and "Jellyboy" that his mother, Kathy, had to move him to another school with a vigorous anti-bullying policy

"Thomas used to come home in tears," she says. "He'd sit at the kitchen table and say, 'That's it – I'm not going to eat any more because I must lose weight.'" Kathy is a cook and knows the meals she prepares are balanced. Neither she nor Thomas are snackers, but both have a sweet tooth. "I feel guilty because this should be within my control, but I'd never put him on a diet because I don't want food to become an issue.

"Being chubby runs in our family, and he is bigger than other boys of his age, but I think it's because exercise isn't a regular part of life any more.

"Of course I have to take responsibility as a parent, but I also think schools should do more. After all, a child spends most of the day there."

Primary schools in England and Wales have more than halved the amount of time allocated to PE lessons over recent years. More positively, organisations such as the British Heart Foundation offer schools free child-friendly materials such as the "Nutrition Mission" CD-ROM with activities designed to encourage an interest in healthy food. But the real solution lies closer to home, the BHF's Belinda Linden believes. "Parents underestimate their own influence," she says. "If you take time to be active with your kids, they're likely to become active parents themselves, but it's going to mean turning a tide in our culture. We've become much too comfortable doing nothing."

British Heart Foundation: www.bhf.org.uk Weight Concern www.weightconcern.com