While obvious factors such as accessibility of transport and availability of junk food impact our life style and mobility, researchers are trying to find the link between our genetic code and environmental impact.
University of Melbourne and Austin Health Professor Joseph Proietto says they are looking to explain the reaction of genetic codes to food components.
"There is evidence also from humans that much of obesity is caused by environmental factors either in the womb or following birth that can alter the expression of a gene, in other words, whether the gene is working or not."
A person's susceptibility to obesity can be determined in early childhood, sometimes even in their mother's womb.
University of NSW Head of Pharmacology Professor Margaret Morris is studying the impact of mother's weight on her child.
She says more mothers and newborn children are overweight.
"We know that child obesity has now increased dramatically since 1960s. Over 30 per cent of Australian children are either overweight or obese. During the same window mums have become heavier. More than 40 per cent of Australian women are reaching pregnancy either overweight or obese. And that is a new phenomenon … It didn't really happen two generations ago."
Barker IDI Hearts and Diabetes Institute Associate Professor Jonathan Shaw say the population's general appearance is also changing with more people gaining weight.
In his 12-year study Dr Shaw has shown that Australia's average waist circumference increased by 5.3 centimetres.
He says there's greater increase among women.
"It's likely that it's going to continue in the next 10 or 20 years. We are seeing people who were normal becoming slightly overweight, people who are slightly overweight becoming more overweight and obese. If we are seeing still increases in the waist circumference that suggests that we are going to continue to see more diabetes resulting from this, perhaps more heart disease and many of the other complications of obesity that we know that it can cause."
Diagnosing obesity by measuring waist circumference or Body Mass Index - measures of weight corrected for height - in multicultural Australia is a real challenge.
Jonathan Shaw says some need less excess fat to create health problems.
"People from different parts of the world deposit their fat in a different way. Fat that gets deposits underneath the skin is not much of a problem for the heart or for the metabolism. Fat that deposits deep inside, around the organs is a problem and does cause trouble. For example people from India if they have to store some fat they are much more likely to store it deep inside around their organs than they are beneath their skin. And much less of extra total fat is required to those people to start causing problems like heart disease and diabetes."
Statistics by McKinsey Global Institute suggest that by 2030 almost half of our population will be obese.
Diabetes remains the fastest growing chronic condition in Australia. Dr Shaw says the issue of obesity needs to be tackled on a legislative level.
"If we keep the whole of our emphasis on the idea that people need to know that they need to know that they take responsibility and need to make changes for themselves, we'll keep on failing, and we've been doing that for 20 years and it doesn't work very well. It's an important component. We need to do rrrrm things at a societal level, population level. Things related to taxation. We need to find ways of pricing foods so that the healthy foods are the cheapest and the easiest rather than unhealthy food being the cheapest and the easiest."
The Obesity Myth starts on September 4 at 7.30pm on SBS, followed by two more episodes at the same time on Monday September 11 and Monday September 18.
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