For a long time, experts were guessing Australia's obesity rate. Now, a groundbreaking, international study has put a number on nations' girth, with serious implications for cancer rates, the food industry and ageing population.
More than one in four Australians are now obese.
It showed there have never been more obese people in the world, with the number of obese people increasing from 105 million in 1975 to 641 million in 2014.
Australia had most recently estimated the rate to be 27 percent, but this is the first empirical proof.
University of Sydney George Institute for Global Health senior director Bruce Neal said the scale of the problem showed it could not be blamed on individuals.
"The world’s population hasn’t turned into sloths and gluttons," Neal said.
"What has happened is that we now live in a swamp of low-cost, high-calorie junk food that is pushed down our throats by sophisticated advertising programs designed to maximise industry profits."
Neal said the federal government needed to be part of the solution.
"Industry is only partly to blame -- after all, it's required to do pretty much whatever it reasonably can to benefit shareholders," Neal said.
"Government ultimately controls what is acceptable corporate behaviour and what is not. And it's government that needs to start taking actions on behalf of the people."
The study showed the proportion of obese men more than tripled from 3.2 percent to 10.8 percent globally, and the proportion of obese women more than doubled from 6.4 percent to 14.9 percent and the rate was predicted to keep increasing.
Cancer Council Western Australia education and research director Terry Slevin said obesity increased cancer risk and this study forecast a corresponding cancer epidemic.
“This is an extraordinary and frightening report which must prompt action," Slevin said.
"With the success in driving smoking rates down, obesity is the most important cancer risk factor for non smokers. On average the population is getting older, and fatter.
"That inevitably will increase the cancer burden."
Slevin said programs to promote healthy weight and policies to restrict the capacity to promote unhealthy food such as taxing sugary drinks, was essential.
"Obesity is a long-term challenge for the health of people around the world. Every country, including Australia, must act to tackle this slow moving but unquestionable public health disaster.
"Australia has been an international leader on tobacco control. We now need to decide if we want to take that same leadership in tackling the obesity epidemic.”
CSIRO health and nutrition research director Manny Noakes said an obese world also used more environmental resources.
"The statistics are alarming and impact not only on increasing chronic diseases globally but also on the environment. Heavier populations consume more fuels as well as food which is not sustainable," Noakes said.
"Appropriate food policies and universal nutrition and healthy weight programs particularly targeting preconception are urgently needed."
Professor Margaret Allman-Farinelli is a Professor of Dietetics in the Charles Perkins Centre at the University of Sydney said it also had implications for Australia's young generations.
"In Australia we anticipate an aging population to be supported by a younger population, who have become overweight and obese sooner than their parents and are more likely to experience the unwanted associated chronic diseases of obesity sooner," Allman-Farinelli said.
"As an example from 1995 until 2012 the percentage of obese 18 to 24 year old women increased from 6 percent to 20 percent."
The study also showed that while the most obese regions were Polynesia and Micronesia, almost a fifth of the world’s obese adults lived in six high-income English-speaking countries -- Australia, Canada, Ireland, New Zealand, the U.K., and the U.S.
"Clearly we live in a world of inequality where those in less affluent nations suffer from lack of nutrient rich foods and those in affluent countries from an oversupply of energy laden and often nutrient-poor foods," Allman-Farinelli said.
"Both are making our world unwell and it is time for better efforts by all government and private sectors to join forces to redress this situation for our global survival."