OVERWEIGHT AND OBESITY

Being overweight or obese increases a person's risk of developing long-term health conditions including cardiovascular disease, high blood pressure and Type 2 diabetes. Being underweight can also be a health risk factor for some people. Body Mass Index (BMI) is a common measure for defining whether a person is underweight, normal weight, overweight or obese.

Data source and definitions In the Australian Health Survey, measured height and weight were collected to determine a person's BMI. For information on how BMI is calculated see Body Mass Index in the Glossary. BMI was only calculated for persons for whom height and weight were measured. For Australia in 2011-12, 83.5% of persons aged 2 years and over had their height and weight measured. This comprises 80.5% of children aged 2-17 who had their height and weight measured, and 84.3% of persons 18 years and over who had their height and weight measured. The results below are based on this measured population only. Adults were classified as being overweight if their BMI was greater than 25.00 but less than 29.99. Adults were classified as being obese if their BMI was 30.00 or more. While the formula to calculate BMI scores was the same for adults and children, the classification of children's BMI was different to that of persons aged 18 years and over, and took into account individual age and sex. BMI cut-off ranges for children 2 to 17 years of age are included in Appendix 4 of Australian Health Survey: Users' Guide, 2011-13 (cat. no. 4363.0.55.001).

Persons 18 years and over

In 2011-12, 62.8% of Australians aged 18 years and over were overweight or obese, comprised of 35.3% overweight and 27.5% obese. A further 35.5% were of normal weight and 1.7% were underweight.

The prevalence of overweight and obesity has increased in Australia over time, from 56.3% in 1995 and 61.2% in 2007–08.

Overweight and obesity varies with age, with 74.9% of people aged 65-74 years being overweight or obese, compared with 36.4% of people aged 18-24 years.

In 2011-12, more men were overweight or obese than women (69.7% compared with 55.7%). However, looking at only those persons who were obese, rates are the same for men and women (both 27.5%). The proportion of people who are obese has increased across all age groups over time, up from 18.7% in 1995 to 27.5% in 2011-12.


The increase in the proportion of people who are overweight or obese is being driven by a general increase in weight and BMI over time. The following graph compares the distribution of BMI scores for people aged 18 years and over between 1995 and 2011-12. This graph shows that not only is there a greater proportion of people who are overweight and obese since 1995, but also that there has been an increase in the proportion of people with much higher BMI scores. For example, in 1995, 5.0% of persons aged 18 years and over had a BMI of 35 and over, whereas in 2011-12 the corresponding proportion was 9.6%.

Between 1995 and 2011-12, the average adult man's weight increased by 3.6kg, while the average adult woman's weight increased by 4.0kg.

Persons aged 18 years & over - Body Mass Index scores(a), 1995 & 2011-12

Footnote(s): (a) Based on Body Mass Index for persons whose height and weight was measured.
Source(s): Australian Health Survey: Updated Results, 2011-12

In 2011-12, men living in inner regional, outer regional and remote areas of Australia were more likely to be overweight or obese (74.4%) compared with men living in major cities (67.7%). This pattern was also consistent for women, with women living in inner regional, outer regional and remote areas more likely to be overweight or obese (63.2%) than women living in major cities (52.5%).


Looking at the level of disadvantage by sex showed that proportionally more women living in areas of most disadvantage were overweight or obese (63.8%) compared with women living in areas of least disadvantage (47.7%). Interestingly, this pattern was not observed for men, with similar overweight or obese rates for men living in areas of most disadvantage (69.0%) and those living in areas of least disadvantage (68.6%).


Children aged 2 to 17 years

In 2011-12, 25.1% of children aged 2–17 years were overweight or obese, comprised of 18.2% overweight and 6.9% obese.

Overweight and obesity rates differed only slightly across children's age groups, ranging from 22.8% for children aged 2 to 4 years, to 26.6% for children aged 12 to 15 years.

The proportion of children aged 5-17 years who were overweight or obese increased between 1995 and 2007-08 (20.9% and 24.7%, respectively) and then remained stable to 2011-12 (25.7%).

Proportionally, the number of boys who were overweight or obese was not significantly different from the number of girls (24.6% compared with 25.7%).


For more information see Table 5: Body Mass Index, Table 6: Persons who are overweight or obese by remoteness and Index of Relative Socio-Economic Disadvantage and Table 7: Body Mass index by selected population characteristics.

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