Australia ranks among the world’s most obese nations

Obesity is the single biggest threat to public health in Australia, with 14 million Australians either overweight or obese, sparking calls for a disease classification.

Given obesity has overtaken smoking as the leading cause of premature death and illness in Australia, public health experts are calling for our nation to follow in the footsteps of the US, by recognising obesity as a disease.

According to a recent Victorian government health report, if weight gain continues at current levels, by 2025, close to 80 per cent of all Australian adults and a third of all children will be overweight or obese.

Earlier this year the American Medical Association (AMA) voted to classify obesity as a disease, urging doctors and insurance companies to give obesity the status as a chronic disease requiring medical intervention.

The issue was tabled at the annual scientific meeting of the Australian and New Zealand Obesity Society in Sydney last weekend.

The prevalence of obesity in Australia has more than doubled in the past 20 years.

On the basis of present trends, by the time our children turn 20 years of age, they will have a shorter life expectancy than earlier generations simply due to obesity.

Aboriginal and Torres Strait Islander Australians are even worse off, being 1.9 times as likely as non-indigenous Australians to be obese.

Multiple causes of obesity

According to the Australian Institute of Health and Welfare, while many factors may influence an individual’s weight, overweight and obesity are due mainly to an imbalance of energy intake from diet and energy expenditure (through physical activities and bodily functions).

There’s strong evidence for a genetic basis for the development of obesity. Many genes have been linked with a predisposition to excess fat. At least six very rare mutations of single-genes causing severe early-onset obesity have been identified. There are also a number of rare syndromes that cause obesity, among other conditions.

Environmental factors also play a big role in obesity. The steep rise in the incidence of obesity in Australia since the 1970s is more likely due to changes in the social and physical environment. For instance, there is a higher prevalence of obesity in Australian children from low socio-economic backgrounds.

The proximity and volume of fast food outlets and supermarkets also shapes the tendency to overeat. Professor Lesley Campbell, a senior member of The Garvan Institute’s Diabetes and Obesity Clinical Studies group, recently stated the reason we see so many people getting fat is that they carry strong hunger genes while the environment is maxed. “It’s an obesogenic environment that rewards eating,” he said.

“People no longer have to go fishing, or hunting and gathering in order to eat. They just go to McDonalds, or KFC, or the freezer.”

Co-morbidity a major concern

Even more concerning is the level of co-morbidity or secondary complications which can be directly attributed to being overweight or obese. For example, Australians reporting heart, stroke and vascular diseases aged 15 years and over were much more likely to be classified as overweight or obese than those without heart, stroke and vascular disease (65 per cent compared with 51 per cent).

Health disorders in children, such as type 2 diabetes, high blood pressure, asthma, hypertension and sleep apnoea can be directly attributed to childhood obesity.

Cardiovascular disease, diabetes and chronic kidney disease account for approximately a quarter of the burden of disease in Australia, and just under two-thirds of all deaths. These three diseases often occur together and share risk factors, such as physical inactivity, overweight and obesity and high blood pressure. Obesity is even a risk factor for some cancers and musculoskeletal conditions.

Pathway to prevention

Attention to diet and physical activity is important not only for preventing weight gain, but also for weight loss and subsequent maintenance. However for some obese individuals, surgery has been shown to be the most effective treatment option, as are certain medications. A study just published in the British Medical Journal (BMJ) comparing surgical and non-surgical treatment of obesity found that surgery led to greater body weight loss and higher remission rates of type 2 diabetes and metabolic syndrome.