Impact

Prevalence of obesity and overweight in Australia

Adults

Two-thirds (67%) of Australians aged 18 and over had a BMI classified as overweight or obese in 2017-18.⁽¹⁾ The prevalence of overweight and obesity has increased significantly from 56.2% in 1995. More men than women had overweight or obesity in 2017-18 (74.5 vs 59.7%) with rates increasing with age in both sexes.⁽¹⁾ Women living in areas of most disadvantage were more likely to have overweight or obesity than women living in areas of least disadvantage (66% vs 50%).⁽²⁾ There were no significant differences between areas of disadvantage for men. Overweight and obesity rates are also higher in regional areas of Australia compared with major cities.⁽²⁾

Children

The prevalence of overweight in Australian children doubled from the mid-1980s to the mid-1990s and rates of obesity have trebled.^{(3, 4)} Since then levels have continued to increase, but at a slower rate.⁽⁵⁾ Nearly a quarter (24.9%) of children and adolescents aged 2-17 years had overweight or obesity in 2017-18.⁽¹⁾

Children who are classified as obese are more likely to carry that weight into adulthood.⁽⁶⁾

Aboriginal and Torres Strait Islander people

Two-thirds (66%) of Aboriginal and Torres Strait Islander people aged 15 years and over had overweight or obesity in 2012-13.⁽⁷⁾ While the combined overweight/obesity rates for Aboriginal and Torres Strait Islander people aged 15 years and over are similar to those for non-Indigenous people, the obesity rates are significantly higher in this population. Aboriginal and Torres Strait Islander people are 1.6 times as likely as non-Indigenous people to have a BMI classified as obese.⁽⁷⁾ This difference is more marked in women.^{(7, 8)}

In 2018-19, 38% of Aboriginal and Torres Strait Islander children and adolescents had overweight or obesity,⁽⁹⁾ and are 1.2 times as likely to be have a BMI classified as overweight or obese as non-Indigenous children.⁽⁷⁾

Diet and physical activity are both important for maintaining a healthy weight. However, diet is the more important factor. Research shows that physical activity plus calorie restriction achieves virtually the same result in weight loss as calorie restriction alone.⁽¹⁰⁾

Impact of diet, physical inactivity, and obesity on cancer in Australia

Australia’s adult obesity rate is the fifth highest among OECD countries.(11) Adult obesity rates in Australia have nearly tripled in the last 30 years, and if effective interventions are not put in place it is estimated that 7.2 million Australians (34% of the projected population), will have obesity by 2025.⁽¹²⁾

Overlaps in obesity and overweight, and other related risk factors make it difficult to quantify their specific impact on cancer burden. For example, physical inactivity and low fruit and vegetable consumption are independent cancer risk factors, but they also contribute to high body mass, which is another risk factor.

Australian analyses have shown that overweight and obesity and physical inactivity and poor nutrition are responsible for a significant proportion of the cancer burden in Australia^(13-16), second only to tobacco smoking.⁽¹⁷⁾ It was estimated that 4.3% (5,371 cases) of all cancers diagnosed in 2013 were attributable to overweight/obesity 1.6% (1,875 cases) to insufficient physical activity, 1.1% (1,308 cases) to inadequate intake of fruit, 0.2% (247 cases) to inadequate non-starchy vegetables, 2.1% (2,620 cases) to inadequate dietary fibre, and 2.1% (2,663 cases) to consumption of red and processed meat.⁽¹⁸⁾

Health and economic impact

In 2015, high body mass accounted for 8.4% of Australia’s total burden of disease.⁽¹⁹⁾ The disease burden attributable to physical inactivity was estimated to be 2.5%, while dietary factors, including low consumption of fruit, vegetables and fibre, and high consumption of red and processed meat, accounted for 7.3% of Australia’s total burden of disease.⁽¹⁹⁾ The total cost of obesity in Australia in 2011-12 was estimated to be $8.6 billion (in 2014-15 dollars), including $3.8 billion in direct costs (including GP, specialist services, hospital care, pharmaceuticals, and public health interventions) and $4.8 billion in indirect costs (including absenteeism, government subsidies and forgone tax).⁽²⁰⁾ The direct costs of obesity alone were equivalent to approximately 2.6% of national spending on healthcare in 2011-12.⁽²⁰⁾

In Australia, healthcare expenditure has been shown to increase with BMI.⁽²¹⁾ For adults with a BMI between 30 and 35 and those with a BMI higher than 35 annual health spending is 19% and 50% higher respectively than spending on those with a BMI 18.5 - 25.⁽²¹⁾