Overweight and obesity

Overweight and obesity refers to excess body weight. Excess weight, especially obesity, increases a person’s risk of developing chronic kidney disease (CKD) by raising levels of blood pressure and abnormal blood lipids, and placing people at increased risk of cardiovascular disease and type 2 diabetes (NHMRC 2013).

Being overweight or obese can make it more difficult to control or manage chronic diseases. Overweight and obesity is also associated with higher rates of death (AIHW 2017). Evidence has shown that the risk of CKD is almost 1.5 times as high for an overweight but not obese person and almost twice as high for an obese person. Obese women have a higher risk of developing CKD than obese men (Wang et al. 2008).

In adults, overweight and obesity is defined as a body mass index (BMI) of 25–29 kg/m2 and ≥30 kg/m2, respectively.

This report uses BMI to define overweight and obesity. For information on waist circumference, see 'Waist circumference' in Diabetes: Australian facts.

In 2017–18, based on measured data from the 2017–18 National Health Survey:

  • an estimated 67% of Australians aged 18 and over were overweight or obese (36% overweight but not obese, and 31% obese)
  • men had higher rates of overweight and obesity than women (75% men, 60% women) and higher rates of obesity (33% men, 30% women)
  • obesity is more common in older age groups – 16% of adults aged 18–24 were obese, compared with 41% of adults aged 65–74 (AIHW 2020).

After adjusting for different population age structures over time, the prevalence of overweight and obesity among Australians aged 18 and over rose from 57% in 1995 to 67% in 2017–18. This was largely due to an increase in obesity rates, from 19% in 1995 to 31% in 2017–18 (Figure 1).

Figure 1: Distribution of BMI among people aged 18 and over, 1995 and 2017–18

The line chart compares the distribution of body mass index among adults in 1995 and 2017–18, and shows that a greater proportion of adults were overweight or obese in 2017–18. The prevalence of overweight and obesity among Australians aged 18 and over increased by 16.5% between 1995 and 2017–18 – driven by a 63% increase in obesity rates during this period.

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Variation between population groups

  • In 2018–19, 71% (381,800) of Indigenous Australians aged 15 and over were overweight or obese. After adjusting for differences in the age structure between the 2 populations, Indigenous Australians aged 15 and over were less likely than non-Indigenous Australians to be overweight (29% and 35%) but 1.5 times as likely to be obese (46% and 30%) (AIHW and NIAA 2022).
  • The age-standardised proportion of overweight and obesity in 2017–18 for adults living in the lowest socioeconomic areas was 1.2 times as high as that for adults living in the highest socioeconomic areas (72% and 62%) (AIHW 2020).
  • The age-standardised proportion of overweight and obesity in 2017–18 was 70% for adults living in Outer regional and remote areas, 71% in Inner regional areas and 65% in Major cities (AIHW 2020).