Overweight and obesity

Burden of disease

Burden of disease is a measure of the years of healthy life lost from living with ill health or dying prematurely from disease and injury. A portion of this burden is due to modifiable risk factors. Burden of disease analysis estimates the contribution of these risk factors to this burden.

Overweight (including obesity) is the leading risk factor contributing to ill health and death, followed by tobacco use and dietary risk factors (AIHW 2024a). In 2024, overweight (including obesity) was responsible for 8.3% of the total disease burden in Australia. It was linked to 30 diseases, including 17 types of cancers, 4 cardiovascular diseases, 3 musculoskeletal conditions, type 2 diabetes, dementia, asthma and chronic kidney disease (AIHW 2024a).

In 2024, overweight (including obesity) was responsible for (AIHW 2024a):

• 55% of type 2 diabetes disease burden
• 51% of hypertensive heart disease
• 43% of chronic kidney disease burden
• 29% of osteoarthritis burden
• 28% of coronary heart disease.

Where people lived was associated with the total disease burden attributable to overweight (including obesity). In 2018, burden attributable to overweight was 2.2 times greater in the lowest socioeconomic area (most disadvantaged) compared with the highest socioeconomic area (least disadvantaged) (AIHW 2018a).

For First Nations people, 9.7% of total disease burden were due to overweight (including obesity), in 2018 (AIHW 2022). Overweight and obesity was responsible for over 68% of total disease burden due to type 2 diabetes, 65% of burden due to hypertensive heart disease and 55% of chronic kidney disease, in First Nations people, in 2018 (AIHW 2022).

For more information on the burden of disease associated with overweight or obesity, see Australian Burden of Disease Study 2024 and Australian Burden of Disease Study 2018: Interactive data on risk factor burden among Aboriginal and Torres Strait Islander people.

Health expenditure related to overweight or obesity

Health expenditure is money spent on health goods and services. It includes money spent by all levels of governments as well as non-government entities; for example, individuals and private health insurers (AIHW 2025a). Expenditure due to modifiable risk factors refers to health system spending on a burden of disease health condition that can be attributed to people having a particular risk factor. It is not spending on addressing the risk factor itself (AIHW 2025c). Additionally, in this report, estimates of health expenditure spent on treatment and management of obesity is also included.

It is useful to monitor the amount of money spent on health (including health prevention) to help assess the impact of policy changes, variations in health service use, or gaps and inequalities in spending on risk factors and disease outcomes between population groups.

Overweight (including obesity) was the leading risk factor contributing to health spending in 2023–24, of the 20 risk factors included in the Australian Burden of Disease Study (ABDS). 

A total of $10.8 billion was either for spending on health conditions attributed to the risk factor overweight (including obesity) or spent on the treatment of obesity (AIHW 2025b, 2025c). Of this amount:

• almost $800 million was spent on the treatment and management of obesity
• $10.1 billion was spent on health conditions due to overweight (including obesity).

In 2023–24, overweight (including obesity) was estimated to contribute to (AIHW 2025c):

• 57% (around $1.8 billion) of spending for type 2 diabetes
• 46% (around $1.4 billion) of spending for chronic kidney disease
• 31% (around $1.2 billion) of spending for coronary heart disease
• 29% (around $1.4 billion) of spending for osteoarthritis.

In 2023–24, spending on the treatment and management of obesity was (AIHW 2025b):

• higher for females (around $570 million) than for males (around $210 million)
• highest for people aged 30–54, with spending of between $89 million and $103 million.

In 2023–24, spending on the treatment of health conditions due to overweight (including obesity) was (AIHW 2026a):

• higher for males ($5.5 billion) than for females ($4.5 billion)
• highest for those aged 60–79 – in males of this age group, the spending was between $719 million and $847 million while for females of the same age group the spending was between $534 million and $651 million.

Changes over time

Health spending on the treatment of health conditions due to overweight (including obesity) is expected to increase around 8.8% on average per year in nominal terms (or 4.7% on average per year adjusted for inflation) between 2024–25 and 2033–34 (AIHW 2026a).

Comparing with tobacco use, which prior to 2024, was the leading risk factor contributing to ill health and death, health spending on the treatment of conditions due to overweight (including obesity) (AIHW 2026a):

• was 1.7 times higher than spending on health conditions due to tobacco use, in 2023–24
• grew faster than for health care spending on health conditions due to tobacco use in the period 2015–16 to 2023–24 (8.1% compared to 5.6% per year) in nominal terms (or 4.9% compared to 2.5% per year, adjusted for inflation) (Figure 20).

Obesity prevention

Obesity prevention is a shared responsibility between many sectors, including the Australian Federal Government, state and territory governments and non-government partners. The National Obesity Strategy 2022–2032 and the National Preventive Health Strategy 2021–2030 both highlight the need to invest in preventive health initiatives to improve environments and systems that support and empower Australians to live healthier lives. A key aim of the National Preventive Health Strategy is to increase all investment in preventive health to be 5% of total health expenditure across all Commonwealth, state and territory governments by 2030.

There is a strong social, economic and health case for investing in obesity prevention (OECD 2019). Policies that target underlying risk factors such as obesity can help in the prevention and reduction of chronic diseases, as well as reducing healthcare costs in the long-term (OECD 2019).

Hospitalisations related to obesity

Admitted patients are people who undergo a formal admission process in a public or private hospital to receive appropriate treatment, management and care for their conditions.

In 2023–24, based on AIHW analysis of the National Hospital Morbidity Database there were around (AIHW 2025e):

• 27,600 hospitalisations (0.22% of all hospitalisations) with a principal diagnosis of obesity. Of these separations with an obesity principal diagnosis, the majority (94%) had a procedure for obesity, such as bariatric surgery
• 27,700 hospitalisations with an additional diagnosis of obesity
• 55,300 hospitalisations with any diagnosis (principal or additional) of obesity
• 30,300 hospitalisations for people undergoing procedures for obesity (such as bariatric surgery), with about 33,300 total procedures (with multiple procedures occurring for some hospitalisations).

In 2023–24, there were around 541,000 hospitalisations with a supplementary code of obesity. This is equivalent to 4.3% of all hospitalisations. A supplementary code is assigned for chronic conditions that are part of the current health status on admission to hospital, but do not meet criteria for inclusion as a principal or additional diagnosis (AIHW 2025d). These conditions are not actively managed in the episode of care but may impact clinical care.

The number of hospitalisations with a supplementary code of obesity is likely an underestimation of obesity in the hospital setting. Supplementary code assignment for chronic conditions is dependent on clear documentation that the condition (in this case, obesity) is part of the current health status of the patient.

In 2023–24, of admitted patients with a supplementary code of obesity (AIHW 2025e):

• 14% had a principal diagnosis from the International Classification of Diseases 10th Revision (ICD-10) chapter Diseases of the musculoskeletal system and connective tissue.
• 13% had a principal diagnosis from the ICD-10 chapter Diseases of the digestive system.
• 9.0% had a principal diagnosis from the ICD-10 chapter Symptoms, signs and abnormal clinical and laboratory findings.
• 8.4% had a principal diagnosis from the ICD-10 chapter Neoplasms.
• 8.0% had a principal diagnosis from the ICD-10 chapter Diseases of the circulatory system.

For admitted patients with a supplementary code of obesity, the top principal diagnoses included:

• osteoarthritis of the knee
• cataracts
• osteoarthritis of the hip.

Admitted patients with a supplementary code of obesity had, on average, a longer length of stay in hospital compared with patients without a supplementary code of obesity, for 5 of the top 20 principal diagnoses, including (AIHW 2025e):

• Atherosclerotic heart disease of native coronary artery; 4.2 days compared with 2.1 days.
• Cellulitis of lower limb (excludes foot and toe); 6.9 compared with 5.2 days.
• Osteoarthritis of the knee; 3.7 compared with 2.4 days.
• Osteoarthritis of the hip; 3.9 compared with 2.8 days.

For more information on hospitals data and definitions, see Hospitals.

Mortality and deaths related to overweight or obesity

Attributable deaths

In this section, attributable deaths represent the amount of mortality that could be reduced if overweight (including obesity) had been prevented.

Attributable deaths are estimated based on deaths that had an underlying cause of death from the diseases linked to overweight (including obesity) in the Australian Burden of Disease Study (ABDS).

In 2024, around 19,000 deaths (10% of all) were attributable to overweight (including obesity), based on data from the ABDS (AIHW 2026c). Of these, around:

• 7,400 (4.0%) deaths were attributable to overweight but not obesity
• 11,300 (6.1%) deaths were attributable to obesity.

The proportion of attributable deaths due to overweight (including obesity) was the same for males and females (both at 10%) (AIHW 2026b).

The proportion of attributable deaths due to obesity has been increasing since 2011 (from 5.1% in 2011 to 6.1% in 2024), while deaths due to overweight but not obesity decreased slightly (4.6% to 4.0%). Over the same period, after adjusting for age, attributable death rates have remained relatively constant for obesity (from 29 per 100,000 in 2011 to 31 per 100,000 in 2024) and decreased slightly for overweight but not obesity (from 26 per 100,000 in 2011 to 20 per 100,000 in 2024) (AIHW 2026b).

Mortality

Obesity can be either an underlying or associated cause of death. When obesity is recorded on a death certificate, it is most often reported as a contributory (associated) cause of death (AIHW 2024b). Obesity is likely to be under-represented in mortality data, which may be amplified due to differing certification practices across jurisdictions.

In 2024, around 2,200 deaths involved obesity (AIHW 2026b), including around:

• 400 deaths with obesity as the underlying cause of death
• 1,800 deaths with obesity as an associated cause of death.

Between 2011 and 2024, the age-standardised rates increased from (AIHW 2026b):

• 5.4 per 100,000 to 8.1 per 100,000 for males
• 4.8 per 100,000 to 6.0 per 100,000 for females.

Trends in deaths recorded as relating to obesity should be interpreted with caution due to changes in death certification practices over time.