The disease burden of overweight, obesity and poor diet
Excess weight is second only to smoking as a modifiable risk factor for ill health in Australia
Overweight and obesity contribute to a high proportion of the burden from type 2 diabetes, hypertensive heart disease and chronic kidney disease
People in lower socioeconomic groups experience the greatest burden of disease linked to excess weight and poor diet
Global disease burden from excess weight and poor diet
An estimated 5.02 million deaths around the world were attributable to high body mass index (BMI) in 2019.1
Dietary risks were responsible for an estimated 7.94 million deaths among adults (≥25 years) in 2019.1 In this study, dietary risk was measured as an aggregate of risk factors:
- diet low in whole grains, fruit, fibre, legumes, nuts and seeds, omega-3 fatty acids, polyunsaturated fatty acids, vegetables, milk, and calcium; and
- diet high in sodium, trans fats, red or processed meat, and sugar-sweetened beverages.
These are dietary patterns that increase the risk of non-communicable diseases.
To calculate combined fatal and non-fatal burden of disease, researchers use the concept of ‘disability-adjusted life years’ (DALYs), which assigns a numeric value to the years of healthy life lost due to illness. For example, four years lived with a chronic illness might become 2.7 DALYs.23
On a global scale, excess weight and poor diet contribute to considerable disease burden as measured in DALYs. High BMI (>25 kg/m2) was the seventh highest risk factor and contributed 160 million DALYs in 2019.1 Poor diet was the fifth most common risk factor and contributed to 188 million DALYs in 2019. The diseases most commonly attributable to excess weight and poor diet were cardiovascular diseases, diabetes and/or kidney disease, and cancers.4
Disease burden from excess weight and poor diet in Australia
In Australia, overweight and obesity were responsible for 8.4% of the total burden of disease in 2018. This represents the impact of people dying early and living with illness due to conditions caused by excess weight, which was surpassed only by smoking (8.6%) as a modifiable risk factor for ill health. The rate of total burden attributable to excess weight was relatively steady over time. In 2003 there were 15.2 DALYs (per 1,000 people) attributable to overweight and obesity compared to 14.5 DALYs in 2018.5
Dietary risks further contributed to Australia’s burden of disease, accounting for 5.4% of the burden. The estimated burden of disease from dietary risks has decreased over time. In 2003, 16 DALYs (per 1,000 people) were attributed to dietary risks compared to 9.2 DALYs in 2018.5
Top five risk factors contributing to burden of disease in Australia, 2018
Australian Institute of Health and Welfare. 2021. Australian Burden of Disease Study: impact and causes of illness and death in Australia 2018. Canberra, Australia.
The total burden of disease attributable to overweight and obesity in Australia includes fatal burden, mainly as a result of cancers, coronary heart disease, stroke and chronic kidney disease. For other conditions such as back pain and osteoarthritis, the burden was non-fatal.6
An analysis that split the Australian population into five socioeconomic groups found the lowest socioeconomic group experienced the greatest burden of disease attributable to overweight and obesity. The burden progressively declined in each quintile so that the highest socioeconomic group experienced the least burden.6 The same was true for dietary risk factors.7 After adjusting for the age structure of different socioeconomic groups, the burden in the lowest socioeconomic group was 2 times that of the highest socioeconomic group for both risk factors.6
Overweight and obesity in Australia contributed to 55% of the total burden (in DALYs) from type 2 diabetes, and a substantial proportion of the burden from hypertensive heart disease, chronic kidney disease, coronary heart disease burden and osteoarthritis, in 2018.6 All dietary risks combined contributed to 50% of the burden from coronary heart disease and substantial proportions of that from bowel cancer, type 2 diabetes and stroke.7
Overweight (including obesity) was the strongest risk factor (7.4%) for non-fatal burden of disease in Australia in 2018, measured as years of healthy live lost to disability. It was the second-highest risk factor for fatal burden (9.6%), as measured by years of life lost. Dietary risks contributed to 8.8% of the total fatal burden of disease in Australia in 2018.5