A federal move towards banning junk food marketing to children needs community support or action could be delayed for another decade, nutrition expert Clare Collins says.
As the government seeks to tackle alarming rates of obesity, diabetes and mental health conditions, junk food marketing is increasing.
Marketing had led people to believe that "happy kids eat junk food", said Laureate Professor Collins, of University of Newcastle.
"Kids are basically defenceless. Adults are supposed to look after them.
"There's evidence to act against Big Food [multinational food corporations]."
The federal government last month released a feasibility study on options to limit unhealthy food marketing to children.
The study proposes banning junk food advertising to children from 5.30am to 11pm on broadcast media.
Marketing of unhealthy food online and on packages would be "restricted".
Submissions to the study close on Friday.
Professor Collins believed most people would agree that children should "not be the victims" of targeted junk food marketing.
She deplored junk food being used to sponsor sick children, sport and school programs.
"Some of the strategies are so sneaky," she said.
"We should all be united in not wanting these very profitable companies harming our children's health."
The latest data shows two in three adults and one in four children in Australia are overweight or obese.
Healthcare costs for overweight and obese adults were estimated to be at least $350 million in the Hunter New England district last year.
The feasibility study stated that about 40 per cent of children's energy intake was from "discretionary foods and beverages".
Fewer than one in 10 children ate the recommended amount of vegetables.
Professor Collins said it was "time for strategies to prevent the marketing of unhealthy food and sugar-sweetened drinks to children".
"This isn't about a nanny state or being mean, this is about caring for the health and wellbeing of children.
"It's about saying it's unacceptable for industries to be targeting your children with foods that do not support their health, wellbeing, growth and academic performance."
She said it seemed like the government was listening, having invited consultation on the issue.
"If we don't make a strong concerted approach, the door might shut for another decade," she said.
The consultation paper said the food sector spent $386 million in 2022 on marketing in Australia.
This spending rose by 45 per cent from 2018 to 2023.
Professor Collins said "another alarm bell" in the study was that more junk food marketing was targeted towards disadvantaged areas.
She was also concerned that parents could be unaware of their children being saturated with junk food marketing while online.
The study said that excess body weight in childhood and adolescence was associated with an increased risk of numerous diseases.
This included type 2 diabetes, fatty liver disease, respiratory illnesses, coronary heart disease, orthopaedic complications and mental health conditions.
Obese children and adolescents were about five times more likely to be obese in adulthood.
