A major survey of Australian secondary schools students in 25 years has revealed a 'chronic disease time bomb', warn experts.
Nearly a quarter of 13-to-18-year-olds are overweight or obese, according to the survey of 12,000 secondary school students, which said Australia was facing a "chronic disease time-bomb".
"If ever there was a wake-up call for Australians, this is it," said Professor Ian Olver from the Cancer Council of Australia, which commissioned the National Secondary Students' Diet and Physical Activity survey.
"As obese kids move into adulthood, the heightened risk of chronic diseases like cancer means previous gains in life expectancy may be reversed.
"We may see today?s teenagers die at a younger age than their parents? generation."
The study found an "excessive prevalence of overweight and obesity among students", with 23.7 percent of the teenagers above their healthy weight.
Just 15 percent met national guidelines for an hour's physical activity every day, with girls more lax than boys and exercise levels diminishing with age.
Almost one in three students said they drank four or more cups of sugary or sports drinks per week, and 43 percent ate fast food or takeaways at least once a week. Only 14 percent ate the recommended amount of fruit and vegetables.
Nearly half (47 percent) of students had three to four televisions in their home, with a further 17 percent reporting five or more TVs and 47 percent saying they had a set in their bedroom. Only one percent had no TV at all.
A majority (71 percent) engaged in "small-screen recreation" -- watching television and DVDs, playing video games and using computers -- for more than two hours on an average school day, exceeding national health guidelines.
"This piece of research confirms what we've feared for some time -- that the high school students of today will grow up to be the heart attack victims of tomorrow," said Lyn Roberts, head of the National Heart Foundation, which co-commissioned the research.
Australia is one of the world's fattest nations, with the most recent National Health Survey classifying 25 percent of people aged 18 or older as obese, and 37 percent as overweight.
The total cost of obesity, including health and productivity costs, was estimated to be around Aus$58 billion ($58 billion) a year in 2008, the most recent available figures.