Changes to voluntary industry codes means junk food will not be promoted during television programs that attract a child audience of at least 35 per cent.
The campaign to stop junk food advertising will be widened by some of Australia’s largest food companies in a bid to cut childhood obesity.
The current Australian Food and Grocery Council (AFGC) restrictions apply to programs with a child audience of 50 per cent.
However, critics say the restrictions do not go far enough and warn that children will still be hounded by unhealthy food ads, news.com reported.
"It does not go far enough to reduce exposure because it won't actually pick up programs that are watched by the greatest number of children overall," Obesity Policy Coalition executive manager Jane Martin said.
It is believed shows like Big Brother, The X-Factor and Junior Masterchef , all have a high number of younger audiences.
Company websites will also be affected with those directly marketing to children under 12 only able to promote healthy alternatives.
Nestle, Mars, Campbell Arnott's, Coca-Cola, Kellogg's, McDonald's and Hungry Jack's are all companies who support the industry's Responsible Children's Marketing Initiative.
However, health experts have slammed the self-regulation of the food industry, saying children are being bombarded with advertisements for junk food.
According to a new study by the University of Sydney and the Cancer Council the number of junk food ads aimed at children has not slowed.
The study looked at all ads on three television channels over five years and found children were exposed to the same number of advertisements for junk food brands now as they were before ''regulation''.
''We know that parents have the most important role to play in terms of what kids eat but it is a bit like road safety,'' Chapman, a nutritionist and director of health policy at the Cancer Council, said.
''Parents can teach their children road safety but it doesn't mean we don't also have speed limits and crosswalks to make their job easier.
“Messages for unhealthy foods on television, the internet … means there are lots of ways messages from parents are being undermined.
''These studies combined show industry codes of practice are not having an impact and we are seeing such big loopholes for the food industry to get away with this.”
Meanwhile, a poll by the Australian National University on attitudes to food security found more than 75% of Australians support a ban on junk food advertising in children’s television, and almost 20% support a total ban.
Earlier this year, Cristel Leemhuis from the AFGC told Food Magazine the industry was part of the solution in improving the rate of childhood obesity.
“Responsible marketing to children is absolutely essential, so we do limit what children see in this area, and the research is very much showing that marketing in those areas decreased dramatically since we implemented that in 2010,” she said.