Australian kids are becoming obese because they spend too much time on their backsides watching TV, new research shows.
And as with most bad habits, it only gets worse with age.
The amount of time children spend sedentary - that is with little or no physical activity - jumps from four-and-half-hours a day between the ages of three and six years to nearly eight hours by 18, according to Dr Dale Esliger from Britain's Loughborough University.
"Methods of counteracting the incline need to be developed, based upon an improved understanding of the phenomenon," he said in a statement on Wednesday.
Dr Andrew Atki, from the UK Centre for Diet and Activity Research, said many things can be done around the home environment to get the kids active.
He said it's important for parents to limit TV and movie watching, particularly on the weekends, and to increase family participation in sports.
Dr Amanda Staiano, from Pennington Biomedical Research Centre, said having a television in the bedroom was negatively impacting people's health.
"Television in the bedroom and watching more than two hours a day are associated with greater odds of elevated waist circumference," she said.
"Reduced television viewing could protect our youth."
Experts will gather in Sydney over the next four days at Be Active 2012 - a sports medicine, sports science, injury prevention and physical activity promotion conference.
One of the main topics of discussion will be the need to encourage more exercise amongst young Australians to curb a growing trend in obesity.