In a study from the University of South Australia of more than 293,770 teenagers aged 12-17 – from 73 countries, across five world Health Organization (WHO) regions – researchers assessed habit clustering, including exercise, healthy food consumption and screen time, finding that:
- 85 per cent did not get enough exercise
- 80 per cent did not eat enough fruit and vegetables
- 50 per cent regularly consumed fast food
- 39 per cent had too many soft drinks
- 32 per cent spent excessive time on screens.
Overall, more than 92.5 per cent of teenagers reported two or more unhealthy behaviours, which puts them at increased risk of developing chronic diseases like obesity, heart disease and diabetes.
Specifically, 7 per cent of teenagers reported one unhealthy behaviour; 30 per cent of teenagers had two; 36.5 per cent had three; 21.5 per cent had four; and 4.5 per cent had five unhealthy behaviours. Across all WHO regions, less than 1 per cent of teenagers exhibited no unhealthy behaviours.
It’s timely research in light of the South Australian Government’s new ’LiveLighter’ campaign to tackle obesity.
Lead researcher, UniSA’s Dr Ming Li, says behaviours that are set up in teenage years lay the groundwork for behaviours in adulthood.
And when a cheeseburger costs less than a punnet of strawberries, the odds are stacked against teens’ healthy choices.
“The teenage years are a critical window for growth and development – physically, mentally, and emotionally – and they set the foundation for long-term health,” Li says.
“But with junk food so readily available, and physical activity often replaced by screen time, more teens are picking up multiple unhealthy habits that could lead to serious health issues down the track.”
The study found distinct differences between regions.
Teenagers in higher-income countries – including the Americas and Eastern Mediterranean – were more likely to report a higher number of unhealthy behaviours, with 13 per cent of teenagers in these regions recording all five risk factors.
While Australian data was not specifically assessed, Li says that Australian teenagers would likely report multiple unhealthy lifestyle behaviours, akin to those seen in other high-income countries.
She says these trends are driven by broader societal shifts.
“Some of what we see comes down to rapid urbanisation, sedentary school environments, and limited access to safe recreational spaces, particularly in low- and middle-income countries,” Li says.
“On top of this, taste preferences, household income, and limited availability of fresh produce – especially in disadvantaged areas – make healthy choices harder to access and maintain.”
While the study reports multiple unhealthy lifestyle behaviours for most teenagers, it also finds some protective factors that can help.
“When teenagers have supportive families and a supportive peer group, their risk of having four or more unhealthy behaviours reduces by 16 per cent and 4 per cent respectively,” Li says.
“Similarly, food-secure households also reduce risk by 9 per cent.”
Li says the findings point to the urgent need for tailored, multilevel strategies that go beyond individual choices to address social and environmental conditions.
“It’s clear we need systemic action – better school-based physical activity programs, urban design that gives teens access to green spaces, policies that make healthy food affordable, and limits on junk food marketing to children,” Li says.
“Ultimately, good health needs to be an easier, more accessible choice – not one that requires privilege, planning, and willpower.”
