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Improvements to labelling are likely to have an impact on Australia's obesity problem, experts say. Photo: Supplied

The federal government should not back away from imposing stringent labelling standards on food if it is serious about tackling obesity, an expert said on Thursday.

Gary Sacks, a research fellow at the World Health Organisation centre for obesity prevention at Deakin University, said research suggested improvements to labelling was one of the measures likely to have an impact on Australia's obesity problem, along with taxing unhealthy food, particularly soft drinks, and restricting junk food marketing to children.

Dr Sacks said the government should honour Labor's vow to make a star labelling system, which rates food healthiness, compulsory after two years if uptake of the scheme in the industry was not good enough.

''Obesity rates continue to rise all around the world, and I think it's clear that unless governments take decisive action there isn't much hope that we can reverse this,'' he said.

Dr Sacks will speak at the second annual Obesity Summit in Canberra on Friday about the evidence that fiscal and legislative changes can have on obesity.

The summit brings together researchers, policy makers and business groups. An Organisation for Economic Co-operation and Development report last week found Australia was the fourth fattest nation on Earth. Dr Sacks said the previous government warranted criticism for its handling of obesity levels, because it had hardly implemented any of the recommendations related to the problem from its own Preventative Health Taskforce.

But it had made good progress on working towards introducing front-of-package food labelling. ''Unfortunately, the current government seem to be making noises that they might be backing away from what the previous government agreed, and that's under strong pressure from the food industry,'' he said.

''It seems like the government is backing away from that promise to ever mandate it, although they haven't made an official announcement.''

Dr Sacks said modelling showed that if even 2 per cent of the population shifted to consuming healthier products as a result of different food labelling, it would be cost effective for the government.

''It will make it easier for people to understand the healthiness of food products, and I think that's really important to the liberal philosophy of empowering people to make their own choices,'' he said.

Philip Clarke of the University of Melbourne's school of population health said international evidence suggested it would be more effective for governments to prevent obesity earlier than they did currently.

Professor Clarke said a US study which offered an intense intervention to people with diabetes and high body mass indexes found they were able to maintain some weight loss over time but there were no benefits in preventing cardiovascular disease, suggesting prevention measures did not work well for that group.