A community programme which aims to encourage obese children to be more healthy has proved highly successful, a study has found.
The children were taught about healthy eating
A year after the nine-week programme, the eight to 12-year-olds were fitter healthier, and more confident.
Details of the Mend programme, now running in 100 areas across England, will be presented to an obesity conference in Budapest on Monday.
One expert said the scheme could underpin work to cut childhood obesity.
Around 30% of UK children are now considered to be overweight or obese.
The trial of the Mend programme (which stands for Mind, Exercise, Nutrition, Do-it!) involved 107 moderately obese children.
The programme involves the whole family and aims to teach both parents and children about healthy attitudes and behaviours relating to eating and activity, and to help children see being active as fun.
Matthew Williams lost weight on the Mend programme
About 1,000 children have now been through the Mend programme.
One of them is Matthew Williams, now 16, who said the fact that his mother, Helen Ball, was also involved in the programme gave him extra confidence.
She said it had taught Matthew, aged 11 at the time, how to eat healthily.
"It involved lessons about nutrition and diet and how to analyse food labels and food items so that you were in control of how much fat, salts and sugar you were taking in so that you could make the right choices," she said.
Over the next three years, it is hoped 26,000 can take part in 300 areas.
Funding for the scheme, which will cost £11m in total, is coming from the Big Lottery Fund, Sainsbury's and Sport England.
Paul Sacher, research director of the programme and an honorary specialist dietician at Great Ormond Street Hospital, said the focus of the programme was not weight loss.
"We do measure them, but their weight is just one of the things we measure. It's more about living healthily."
That is presented to children in ways which they can relate to, such as not being picked last for sport and being able to fit into jeans.
In the study, half were put through the programme, while the rest had no interventions.
After six months, children in the programme had a waist measurement which was, on average, just over 4cm smaller than those in the non-intervention group.
The programme group also had a body mass index measure which was two points lower and did at least three more hours of physical activity per week.
Tests also showed their confidence increased by 10%.
Twelve months after being on the programme, the children still showed significant benefits in their weight, fitness and wellbeing, although natural growth meant the figures are not directly comparable to their original measurements.
After the initial study period, the children in the non-intervention group were also put through the programme because of its success.
Mr Sacher said: "We were delighted to see that the results were largely sustained at 12 months.
"Obviously sustaining a healthy lifestyle is the Holy Grail of health and fitness."
Louise Diss, from The Obesity and Awareness and Solutions Trust (Toast), praised the programme for looking at more than just food and exercise.
"The fantastic thing is that along with Toast philosophy, what they do is look at the physical and the psychology at the same time," she said.
Professor Alan Lucas, director of the Medical Research Council Childhood Nutrition Research Centre at the Institute of Child Health, said: "Obesity is an immense public health issue in both immediate and long term health.
"It costs the nation £7 billion a year.
"This popular community-based programme has the potential to underpin effective national strategies for obesity treatment and prevention."