It’s hard to say no all the time. What parent doesn’t sometimes give in to endless whining and sleeve-tugging for lurid sweets and garish drinks? Pester power has chalked up another victory. But the Devil doesn’t have all the best tunes. Most children can chant the “five a day” mantra and they are learning that fruit is fun and that you can make friends with salad.

Give them a chance and many children may decide that sickly sweets or fatty foods aren’t what they always want to eat. There’s an apocryphal school-gates story about the mum spotting her child with an apple and shouting: “Oi, stop eating that; you won’t want your chips later.”

The obesity epidemic has to be tackled by changing eating habits in families. One teacher says that many parents’ immediate reaction is “He won’t like that”, if it’s suggested that a child could try a vegetable. Someone else has to convince the child to eat healthily; then the child can persuade the rest of the family. After all, it works the other way round, with junk food.

In a survey of 1,000 children and 1,370 parents carried out by Sainsbury’s for its Active Kids initiative, which provides exercise equipment and training for schools, 87 per cent of parents admitted that their children influence the food they buy. They’ve got the power. Now more and more kids are making the pestering more positive.

The survey revealed that two out of three parents had been asked by their children to buy healthier food. More than half had asked for fruit instead of crisps and chocolate. They’ve been putting in requests for more fresh food and asking if they can cook healthy meals themselves. Families under pressure from their children are feeling the effect of positive pester power; 57 per cent of those surveyed are eating healthier food and more than a third are doing more things together as a family.

The best pests are the 8 to 10-year-olds, who are most receptive to what they’re told at school. According to Dr Pat Spungin, founder of www.raisingkids.co.uk and its Back to the Table campaign, children are more clued-up about food than ten years ago. Many families watch television cookery programmes together, prompting children to expect better food at home. If only children learnt to cook.

In the absence of compulsory cookery lessons in schools, Let’s Get Cooking is a new National Lottery-funded initiative which aims to set up a network of after-school cookery clubs across the country to educate children about eating well. Although intended mainly for children, the idea is to equip children and parents with cooking skills as a way of changing what they eat, says Wendy Carter, the communications manager at Let’s Get Cooking. Meanwhile, as children become better educated about food and nutrition, plenty of parents are only too happy to give in to healthy pestering. www.letsgetcooking.org.uk One day, Noah Carr, 9 (pictured right with his brother Isaac, 6), came home from school and asked his mother if they could have sushi instead of fish and chips for tea. Perhaps his mother Patty Carr, a district nurse, shouldn’t have been surprised.

Noah and Isaac had been dragging her towards the pulses in Tesco, looking at the kidney beans, bulgar wheat and couscous they’d eaten for lunch, and keeping an eye on her fat intake, too.

It started about 18 months ago when they took up school dinners at St John’s Catholic Primary in Poulton-le-Fylde, Lancashire. “Healthy eating is a huge part of everything they do now,” says Patty. “The dinner ladies are part of the team and know what the children have eaten. They learn about different types of food and what is good for your body. The children know protein builds their muscles and carbs keep you going.”

Patty owns up to a weakness for thickly buttered bread. “They tell me about cholesterol and Noah said: ‘Mummy, that’s an awful lot of butter’.” She admits that she was stumped when they asked where the lentils in her homemade soup came from and is being kept on her toes in the kitchen. “Once they might have said, ‘Can we have chips?’ Now they’re asking me what’s good for them.”

Since watching the chicken nugget autopsy on Jamie’s School Dinners, the boys want to know what’s in processed food, and now that Patty has realised how easy nuggets are to make herself, she can’t imagine buying them. Or fish fingers or burgers. “I used to get frozen meals such as shepherd’s pie and they weren’t that tasty, but I haven’t bought them for a couple of years.”

Vegetable sushi will join her repertoire of regular meals. The children had a go with their head teacher on her return from a trip to Japan, and at home they all joined in the preparation before eating with chopsticks, sitting around the coffee table on the floor.

Cooking with the children has been safer since Noah came home flourishing a food hygiene certificate. “What the teachers tell them about food really counts,” says Patty, whose son now willingly washes his hands.

“We save £30 a week by not eating takeaways and we’ve discovered jacket potatoes and steamed veg instead”

“I can’t praise the school enough for the hard work they’ve done,” says Jayne Withers. The Annie Lennard Infant School in Smethwick, the Midlands, has made a big difference to her children Harry, 7, and Emily, 9. “If the children hadn’t been there we’d probably still be living on junk.” No sweets are allowed in school. A tuck shop sells toast, crumpets, water and fruit juice. Healthy activities are rewarded with stickers. “They’ve designed a sandwich, tried different smoothies; we’re winning them over,” says Julie Wiseman, a learning support practitioner at the school.

Jayne says: “Now the children nag their parents to do the right thing.” Harry is an enthusiastic convert. “He’s always been a finicky eater and we used to send him in with a packed lunch that was predominantly junk – a Penguin bar, crisps – but he didn’t eat it,” Jayne admits. Since the sandwich-making session, he has renounced white bread for a half-wholemeal sandwich and supervises the contents of his lunchbox to make sure there are satsumas, bananas or grapes. Any rogue chocolate biscuits will come back untouched.

The whole family has benefited. From two or three takeaways a week they’re down to one, and they have discovered jacket potatoes and steamed veg. “And cost-wise we’re better off without a pizza, Chinese or Indian,” Jayne says, adding that they save £30 a week with their new healthy eating habits.

“I’m tempted to make a quick microwaved meal, but the kids won’t let me”

When Carolyn Gilbey, and her children Katya, 10 and Ben, 11, moved back to North London from America a year ago, the UK crisps, sweets and chocolates proved tempting and their diet suffered accordingly.

But then the influence of Katya’s school began to kick in. “Katya has become strident about healthy eating,” says her mother. “She’s asked me not to buy crisps and we don’t keep chocolate at home.” After school she and Ben relish nothing more than an apple.

Carolyn is a reluctant cook, but the children insist that they have freshly made and healthy stir-fries, grilled meat and fish. As Carolyn laments: “I do feel tempted to stick on a microwaved meal, but they won’t let me get away with it.”

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