Children who engage in daily physical exercise reap the health benefits as early as their teens, according to a study that will bolster calls for a national response to obesity.
The study of 4600 children found those who were more active in late childhood had a lower body weight and lower risk factors for cardiovascular disease and diabetes by their mid-teens.
University of Sydney researcher Emmanuel Stamatakis said the results demonstrated the importance of exercise for children.
"The main value of this study is that it shows the fact that inactivity seems to compromise the cardiometabolic system from a very young age," Associate Professor Stamatakis said.
"We want children to be active, not so much so they don't get chronic disease as children, but we want them to be active for health in their adult life because that is when chronic disease happens."
Encouraging physical activity in children would require a national approach that involved various government agencies working together.
"The health sector needs to talk to the education sector and perhaps the sports sector as well," he said.
"The problem of chronic disease cannot be solved by one or two measures."
The research involved in a British longitudinal study published in Pediatrics.
Each child was asked to wear a motion sensor for seven consecutive days during waking hours at the age of 11, when measurements and blood samples were taken.
They were measured and tested again at the age of 15, and the results were controlled for genetics, diet and other health risk factors.
Those who engaged in at least 60 minutes of moderate to vigorous exercise each day at age 11 had better cardiometabolic health, less body fat and a reduced risk of diabetes at age 15.
However, the most sedentary children did not have worse health outcomes by their teens.
Associate Professor Stamatakis said these least active children may suffer from poorer health in adulthood, though the results should be taken at face value.
Obesity Australia executive director Stephen Simpson said a combination of measures to encourage physical activity would be more effective than those operating in isolation.
These could include "walking buses" to school, redesigning playgrounds or changes to the school curriculum.
"You could come up with endless things, but what you want is to put them together and get a community change," Professor Simpson said.
The network of influences on obesity, charted by the British Foresight Project in a spaghetti map, proved that a multi-pronged approach was required, he said.