A major new study has found that children and adolescents consume significantly more calories after watching just five minutes of junk food advertising—regardless of whether it’s a flashy TV commercial or a static image on a billboard.
Presented this week at the European Congress on Obesity in Spain, the randomised crossover trial revealed that young people aged 7 to 15 consumed, on average, an extra 130 calories in a day after viewing advertisements for high-fat, sugar and salt (HFSS) products. That’s roughly the equivalent of two slices of bread—and enough to trigger gradual weight gain over time.
“Our findings offer crucial novel information on the extent, nature, and impact of unhealthy food marketing via different types of media on young people’s eating behaviour,” said lead author Professor Emma Boyland from the University of Liverpool in the UK.
“Even short exposure to marketing of foods high in fat, salt, and sugar can drive excess calorie consumption and potentially weight gain, particularly in young people who are more susceptible to advertising and whose eating patterns influence their lifelong health.”
Crucially, the study also found that so-called “brand-only” advertising—featuring logos and mascots without showing any actual food—was just as effective as product-specific ads in boosting kids’ consumption. Audio, static, and social media content all had similar effects, and children with higher body mass index (BMI) scores were even more likely to overeat.
Researchers tested the effects on 240 children from schools in Merseyside, UK, exposing them on two separate occasions to five minutes of HFSS and non-food ads. Across the board, children ate significantly more after seeing the unhealthy food content: an additional 58.4 calories from snacks and 72.5 calories from lunch on average.
“Our results show that unhealthy food marketing leads to sustained increases in caloric intake in young people at a level sufficient to drive weight gain over time. This study is the first to demonstrate that brand-only food ads, for which there is currently no restrictive advertising policy globally, increase children’s food intake. This new knowledge will help in the design of urgent restrictive food marketing policies that can protect children’s health,” said Professor Boyland.
Growing Pressure at Home
The findings add to mounting pressure in Australia, where public health advocates are urging the next Federal Government to introduce sweeping reforms to protect children from junk food marketing.
Research released last month by Deakin University revealed that 85 per cent of Australian caregivers are concerned about the impact of unhealthy food advertising, with more than 60 per cent backing a complete ban on junk food marketing aimed at children. Nearly half support restricting TV advertising before 9pm, and removing child-targeted packaging such as cartoons.
“The results show that Australians are concerned about the current situation when it comes to junk food advertising in Australia—and rightly so. Our children can’t walk to school, go to the shops or sit down and watch TV without being bombarded with unhealthy food advertising and it’s affecting their health. Childhood obesity rates are increasing, while preventable disease in our community continues to grow,” said senior author Professor Kathryn Backholer.
Obesity has now overtaken tobacco as Australia’s leading cause of preventable disease, according to the Public Health Association of Australia. CEO Adjunct Professor Terry Slevin described it as “a public health ticking timebomb” and called for firm commitments from all federal election candidates.
“When are we going to stop focusing exclusively on health treatment, Medicare, hospitals and urgent care, and do more to keep all Australians, particularly our future generations, healthy and well? That’s why we are asking the next Federal Government to take meaningful action on obesity prevention—including stopping our children’s health being damaged by unhealthy food and drink companies,” Slevin said.
States Leading the Charge
Some states are already taking steps. From July 1, South Australia will ban junk food advertising across Adelaide’s public transport network in a bid to curb rising obesity levels. The policy follows Cancer Council SA data showing that nearly 80 per cent of food ads on buses promote unhealthy products.
Chris Picton, Minister for Health and Wellbeing, said the move was sensible given the health concerns attached.
“Each year, big brands spend millions of dollars on catchy slogans and appealing ads that encourage our children to consume more highly processed, unhealthy foods,” Picton explained.
“Banning these ads in some of the key places they are seen regularly – especially by children – is a sensible step towards a healthier South Australia.”
“The rising rates of obesity are concerning, which is why we have developed an evidence-based policy to restrict the advertising of unhealthy food and drinks on State Government buses and trams,” Picton said.
“This policy recognises that the cumulative exposure of unhealthy food and drink advertising influences a child’s food preferences and intake and the associated pester power children use to persuade parents.”
But other states are lagging. In Victoria, Cancer Council Victoria is urging the government to introduce similar restrictions ahead of the Metro Tunnel’s opening. A recent survey found two-thirds of parents support removing junk food advertising from public transport, yet the government has so far refused to commit.
“The processed food industry has been left to make its own rules for too long, and its actions put corporate profits ahead of children’s health. The sooner government steps in to protect children from the sheer volume of powerful advertising, the sooner we can start to create a healthier environment for our kids to grow up in. We can’t afford to wait,” Jane Martin, executive manager of the Food for Health Alliance.
With new data showing that even fleeting ad exposure can shape children’s eating habits, experts say the evidence base is now too strong to ignore.
Industry fights back
The potential ban does have some opposers however. The Australian Association of National Advertisers (AANA) has urged the South Australian Government to reconsider its sweeping ban on food and drink advertising on government assets, set to take effect from 1 July 2025.
If the ban goes ahead, the AANA is calling on the South Australian Government to adopt a science-based approach, such as the Food Standards Australia New Zealand (FSANZ) nutrient profiling scoring criteria, to determine which foods should be restricted.
The current approach lacks scientific backing and could lead to serious unintended consequences for South Australian businesses and a significant loss of advertising revenue for the state’s public transport network.
“This simply doesn’t make sense, and the government should be making evidence-based decisions, not blanket bans that don’t align with nutritional science.”
Similarly, soy milk that has been fortified with calcium and is a core food in the Dietary Guidelines is considered in this policy to be a sugar-sweetened beverage and cannot be advertised. Jam can be advertised, but rice cakes are banned.
“We fully support measures that encourage healthy eating, but this policy fails to distinguish between everyday foods and discretionary items, creating confusion and unfairly restricting brands that are doing the right thing from communicating with consumers,” Faulks added.
The AANA has also raised concerns about the number of businesses covered by the ban. “The policy bans all advertising showing those banned food or drink items. For example, an ad celebrating the anniversary of a children’s charity which depicts a child with a birthday cake would be banned. The Tasting Australia event can no longer show images of charcuterie boards or pastries in their advertising. Under this policy, businesses that have nothing to do with the food or beverage industry will find advertising in South Australia harder,” Faulks said.
The AANA also pointed to proactive steps the advertising industry is taking to encourage healthy eating. The outdoor advertising industry has donated more than $41 million in advertising value to support an industry-led national health campaign over the past five years. South Australia was invited to participate in this year’s campaign.
The AANA is calling on the South Australian Government to reconsider its approach and focus on evidence-based policies that support both public health and economic sustainability.
With childhood obesity now the leading preventable health issue in Australia, public support for tougher advertising restrictions is surging. While states like South Australia are leading with action, others are yet to follow suit. And as industry pushback intensifies, the debate is now at a crossroads.
With the evidence now irrefutable, public health advocates say the time for waiting has passed.
