The 'It's Your Move!' program - an initiative of Deakin University and ACT Health - was run in selected ACT schools over a three year period with the aim of preventing obesity among teens.
The project used three intervention schools and compared them with three 'control sites', targeting students aged between 12 and 16. Data was collected from 656 students, including BMI measurements and self-reported behavioural changes.
At the program's end, two of the three intervention schools showed a significant decrease in the number of students classified as overweight or obese, compared to no change in the control group.
The results were published in the Australian and New Zealand Journal of Public Health.
Lead author Professor Steven Allender, director of the Global Obesity Centre within Deakin's School of Health and Social Development, said the program was unique in that it looked at a whole range of contributing factors to obesity in combination.
"The intervention included multiple initiatives at individual, community and school policy level to support healthier nutrition and physical activity," Professor Allender said.
"Each school developed a 'Food at School' policy that encompassed canteen food, food at sport and fundraising events, and school catering.
"The policy included instigating a traffic light colour coding system for food sold at the canteen, healthy morning teas for staff to encourage positive role-modelling, cooking classes after hours for staff and students, and increased access to water fountains in the school yard."
Each school also picked a key objective, including increasing active transport, increasing time spent physically active at school and supporting mental wellbeing.
ACT Deputy Chief Health Officer, Dr Andrew Pengilley congratulated the three Canberra-based schools: Alfred Deakin High, Calwell High and Melrose High who participated in the pilot.
"The schools achieved a decrease in the proportion of students who were overweight or obese, an increase in the proportion who ate five or more vegetables a day, and an increase in the proportion of students who drank four or more glasses of water at school," Dr Pengilley said.
"It is not easy to achieve an overall drop in overweight and obesity, but the pilot managed that in two schools, with the third school maintaining stable rates.
"These are welcome results that show by engaging school communities in the design of initiatives for their students, we can make positive changes to the health and wellbeing of young people.
"'It's Your Move!' has helped change each school for the long term by embedding healthier practices into their curriculum and policies, so students will continue to benefit from the program into the future."
Professor Allender said the work was critical as obesity affected two thirds of Australia's population and cost $60 billion per year.
"Even more worrying is that some recent studies show rates of obesity among children are as much as double our previous understanding," he said.
"This has significant impacts on mental health, education attainment and employment prospects. But this trial proves that obesity is preventable."
Professor Allender said there was a significant decrease in depressive symptoms at the school that had made a special goal of improving mental well-being through the promotion of healthy eating and physical activity.
"Students who reported symptoms of depression dropped from around a quarter of the group, to just over 17 per cent," he said.
"This is great evidence that modifiable lifestyle behaviours - like what we eat and our amount of daily physical activity - can affect our mental wellbeing.
"Yet the number of obesity prevention interventions that include mental health follow-ups is low. We think this work demonstrates that community interventions can, and should, be multi-purpose.
"Systems thinking is the critical next stage in obesity prevention. We can't keep looking at health promotion activities in isolation from each other. A holistic approach is what is going to get results."
'It's Your Move!' has now been rolled out to 11 high schools in the ACT and 11 communities in South Western Victoria, with a further 100 communities on a waiting list to take part.
Article: School-based systems change for obesity prevention in adolescents: outcomes of the Australian Capital Territory 'It's Your Move!', Steven Allender et al., Australian and New Zealand Journal of Public Health, doi: 10.1111/1753-6405.12696, published 27 July 2017.