Reducing the burden due to overweight (including obesity) and physical inactivity

Every year in Australia, millions of years of healthy life are lost because of injury, illness or premature deaths in the population. This loss is called the ‘burden of disease’.

In 2018, more than one-third (38%) of disease burden could have been prevented by reducing exposure to risk factors such as tobacco use, overweight (including obesity), alcohol use and physical inactivity (AIHW 2021). These and other lifestyle-related risk factors are major contributors to chronic conditions such as coronary heart disease, dementia, type 2 diabetes and cancer.

This AIHW analysis looked at 2 risk factors for disease – overweight (including obesity) and physical inactivity – to see what could happen if Australians reduced their body mass index (BMI) or were more physically active between 2018 and 2030. In 2018, overweight (including obesity) and physical inactivity jointly accounted for 8.7% of the total burden in Australia – greater than tobacco smoking (8.6%), which was the leading risk factor for disease burden in Australia in 2018.

The year 2030 was chosen as it aligns with the National Preventive Health Strategy 2021–2030, which seeks to achieve improved health outcomes over the decade and is complemented by the National Obesity Strategy 2022–2032 (the Department 2021b, Commonwealth 2022).

Australia’s status

In 2017–18, 2 in 3 (67%) adults and 1 in 4 (25%) children were overweight or obese (AIHW 2020a). From 1995 to 2017–18, trends over time have shown an overall increase in people living with overweight (including obesity). Among adults, the prevalence of those living with overweight (including obesity) increased from 57% in 1995 to 67% in 2017–18. The prevalence of obesity among adults similarly increased from 1 in 5 (19%) in 1995 to 1 in 3 (31%) in 2017–18 (AIHW 2020a).

The latest guidelines refer to ‘insufficient activity’ to describe minimum levels of activity required for health benefits (the Department 2021a). Trends in insufficient physical activity among adults have shown a slight decrease from 69% in 2007–08 to 65% in 2017–18 (AIHW 2020b).

Scenarios in 2030

The analyses examined the following scenarios:

• Stable scenario: in 2030 the prevalence of overweight (including obesity) and physical activity in the population stays at 2018 levels.
• Target scenarios: people at increased risk of disease associated with living with overweight (including obesity) and physical inactivity in 2018 reduce their BMI or increase their level of physical activity, respectively, and maintain this to 2030.
• Trend scenario: for overweight (including obesity), current trends in exposure were extended to 2030. However, limited data were available to inform the same trend for physical activity.

The modelling applied the methods used in the Australian Burden of Disease Study (ABDS) 2018 (AIHW 2021).

The analysis found that small improvements to people’s weight and exercise levels could have a big effect on the disease burden attributable to the 2 risk factors:

• If people at risk reduced their BMI by one unit (that is, 1 kg/m²) – which amounts to about 3 kg for Australians of average height – and maintained this to 2030, disease burden and deaths attributable to overweight (including obesity) could fall by 11% across the population, or 60,400 disability-adjusted life years (DALY), and 10% (2,300 deaths), respectively.
• If people at risk did the equivalent of an extra hour of moderate-intensity activity per week, such as taking a brisk walk, and maintained this to 2030, disease burden and deaths attributable to physical inactivity could fall by 16% (28,300 DALY) and 13% (1,500 deaths), respectively, across the population.

The analysis also found that the most effective interventions for achieving greater improvements in disease burden in 2030 would be those targeting higher levels of BMI  (that is, the obese population) and those increasing activity among older people – these are the groups that experience larger disease burden overall.