The expanding waistlines of New Zealand children can be curbed by simply modifying the school environment, a groundbreaking study by Otago University has found.
Yet to be published results from Apple - a two-year study involving around 500 primary school children - have found that children whose schools received physical activity and nutrition education aid were less likely to become overweight, and more likely to have healthier waist circumferences and blood pressure.
The findings appear to validate moves to make schools healthier to avert an obesity epidemic - moves some medical sectors have criticised in the past as costly endeavours based on little medical proof.
Dr Rachael Taylor, who led the Apple study, said few obesity prevention studies in the past have observed any beneficial effect in weight.
"What we're really saying is that previous education-based systems aren't enough, but if you can get a whole-of-community approach like the Apple project, we might actually make a difference."
But the project did not change the outcome for children who were already overweight.
"Getting a positive in both things would've been better, especially if we were actually able to reduce the number of kids who were overweight. But shifting the whole population back a bit is also very important, because that's what we've observed over the last few decades - everybody's getting a little bit fatter. And if everybody's getting a little bit fatter, then that puts more into the overweight category."
Children in the study had waistlines on average 1cm less than the control group and weighed an average of half a Body Mass Index unit lower.
The index is used by researchers to calculate obesity. A study in 2004 showed the mean BMI for New Zealand children aged 11 in 2000 was 19.8 - up from 18.1 in 1989.
A fully grown man would be considered obese if his BMI was above 30. There is no equivalent figure for children because of their rapidly changing body sizes.
When the study was first formulated in 2000, it was structured on the basis that living healthily was difficult for many people, said Dr Taylor.
"We live in an environment that's not conducive to healthy eating and physical activity. There's too many pressures the other way, and what you have to do is not just tell people what they should and shouldn't be doing, but actually change the environment in which they live in so it's easier to make those changes."
Four semi-rural South Island primary schools were selected to receive the Apple "interventions", which included part-time community activity co-ordinators, promotions targeting a reduction in sugary drinks, and the provision of water filters.
Dr Taylor said the co-ordinators recruited parents for school sports and created activity programmes outside the school curriculum. Nutrition classes included lessons on the effects of sugary drinks.
The study did not look at altering the food availability in these schools, as none had a tuck shop.
Palmerston Primary School, located between Oamaru and Dunedin, was one of the participating schools. Principal Elizabeth Cleverley said the project was an "absolute success".
"Playground behaviour improved, and the children were definitely more active."
Line dancing proved to be a big hit among the children.
"They just put on the music at lunchtime and they just did it."
* Four semi-rural South Island primary schools received "interventions" such as physical activity co-ordinators, and promotions targeting a reduction in sugary drinks. Water filters and fruit were also provided. Schools also organised bush walks and beach days, and activities such as school car washes.
* The project did not alter the weight of children who were already overweight.