The disease burden of overweight, obesity and poor diet

Global disease burden from excess weight and poor diet

An estimated 3.71 million deaths around the world were attributable to high body mass index (BMI) in 2021.¹ This was a 43% increase in the number of deaths attributable to high BMI since 2010, and a 3.4% increase in the age-standardised rate of attributable deaths over the same time frame.¹

Dietary risks were responsible for an estimated 7.2 million deaths in 2021.² In this study, dietary risk was measured as an aggregate of risk factors: diet low in whole grains, fruit, fibre, legumes, nuts and seeds, seafood omega-3 fatty acids, omega-6 polyunsaturated fatty acids, vegetables, milk, and calcium; and diet high in sodium, trans fats, red or processed meat, and sugar-sweetened beverages.² 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.³

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 7^th highest risk factor and contributed 129 million DALYs in 2021.¹ I Poor diet was the 5^th highest ranked risk factor and contributed to 178 million DALYs in 2021. The diseases most commonly attributable to excess weight and poor diet were cardiovascular diseases, diabetes and kidney disease, and cancers.^{1 2}

Disease burden from excess weight and poor diet in Australia

In Australia, overweight and obesity were the leading cause of preventable health loss in 2024, responsible for 8.3% of the total burden of disease.⁴ This represents the impact of people dying early and living with illness due to conditions caused by excess weight, which now surpasses all other modifiable risk factors for health, with tobacco use ranked second (7.6%).⁴ 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, age-standardised) attributable to overweight and obesity compared to 14.3 DALYs in 2024.⁴

Dietary risks further contributed to Australia’s burden of disease, accounting for 4.8% of the total.⁴ The estimated burden of disease from dietary risks has decreased over time. In 2003, 15.9 DALYs (per 1,000 people, age-standardised) were attributed to dietary risks compared to 8.1 DALYs in 2024.⁴

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.⁴

An analysis that split the Australian population into five socioeconomic groups found that in 2018, the most disadvantaged 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 due to this risk.⁵ The same was true for dietary risk factors.⁶ 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.⁵

In 2024, overweight and obesity in Australia contributed to 54.5% of the total burden (in DALYs) from type 2 diabetes, and a substantial proportion of the burden from hypertensive heart disease, uterine cancer, gout, chronic kidney disease, gall bladder and bile duct disease, oesophageal cancer, atrial fibrillation, coronary heart disease burden and osteoarthritis.⁴ All dietary risks combined contributed to 49.9% of the burden from coronary heart disease and substantial proportions of that from bowel cancer, type 2 diabetes, stroke and oesophageal cancer.⁴

Overweight (including obesity) was the strongest risk factor (7.1%) for non-fatal burden of disease in Australia in 2024, measured as years of healthy life lost to disability.⁴ It was the second-highest risk factor for fatal burden (9.6%), as measured by years of life lost. Dietary risks contributed to 7.9% of the total fatal burden of disease in Australia in 2024.⁴

Content for this page was reviewed and updated by Melanie Nichols at GLOBE, Institute for Health Transformation, Deakin University.