Obesity rates in Australia and New Zealand have soared by more than 80 per cent in the past 33 years, the biggest increase in a groundbreaking survey of almost 200 countries.
The findings, which reveal almost one in three Australians is obese, intensifies pressure on the government to restrict junk food marketing, restore the healthy food-star rating system and force companies to cut sugar and fat in processed food and drink.
''Waiting for a cure is not possible,'' says Rob Moodie, the professor of public health at the University of Melbourne. ''The public health system will be crushed by the obesity crisis and the rise in cancer, heart disease and diabetes.''
Australia is one of the fattest nations, jumping almost 40 places to 25th in obesity ranking, just behind the US but well ahead of France, Finland, Germany and Japan.
The analysis from the Global Burden of Disease Study 2013 study, led by University of Washington researchers and published in the journal Lancet, examined the rates of excessive weight in adults and children in 188 countries between 1980 and 2013.
It found 29 per cent - or 5.2 million - Australian adults are now obese according to their body mass index, a measure of the relationship between height and weight, compared to 16 per cent in 1980. About one quarter of children and more than 60 per cent of adults are either overweight or obese. One third of women are obese, a 75 per cent increase since 1980.
Obesity, which is defined as having a body mass index of 30 or higher, is linked to higher risk of heart disease, stroke, high blood pressure and bowel, oesophageal and pancreatic cancer.
Saturating children and adults with junk food advertising, particularly through sport, means many parents are ''fighting a battle'' against the junk food industry, Professor Moodie said. ''We have also failed to get anywhere with front of pack labelling, or with food reformulation, because of huge resistance from the industry to anything that might improve our health. Only now are people starting to realise there are 10 teaspoons of sugar in a can of coke.''
The nutrition program manager at the Cancer Council NSW, Clare Hughes, said a ''uniform guide'' to making healthy choices, such as the star rating system, would encourage the food industry to reformulate products and set targets to limit sugar, salt and saturated fat. ''Even small changes in nutrient content to unhealthy food can bring significant change among the whole population,'' she said.
But reversing the obesity trend could be even more difficult given recent budget cuts to programs that target prevention. ''Funding for the National Preventive Health Partnership, which financed school, worksite and community health programs around the states, has been abolished and the proposed co-payments scheme will discourage people worried about overweight from seeing their GPs,'' said Mike Daube, professor of health policy at Curtin University.
''What is really scary is to see the way obesity has crept up on us over the past three decades. We have become the fat country.''
Globally, 2.1 billion people are now overweight or obese, a 28 per cent increase in adults and an almost 50 per cent increase for children since 1980. Not one country has reduced obesity rates in the past three decades and more than half of the world's obese people now live in developing countries.
