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In 2007–08, 61% of Australian adults were overweight or obese, based on measured data, compared to 57% in 1995.

In 2007–08, 24% of Australian adults were obese, based on measured data.

People with a higher body mass index (BMI) are at greater risk for Type 2 diabetes.

Why is this an important indicator for diabetes?

The proportion of Australian adults who do not already have Type 2 diabetes but are overweight or obese is an indicator of Australian adults who are at risk for Type 2 diabetes. Body Mass Index (BMI), based on measured and self-reported height and weight, is used to estimate this (AIHW 2011).

What are the results?

Measured BMI

In Australia in 2007–08:

  • 61% of adults were overweight or obese, based on BMI calculated from measured height and weight (Table 1).
  • 24% of adults were obese.
  • Males were more likely to be overweight or obese than females.

From 1995 to 2007–08:

  • Rates of obese adults increased from 19% to 24%.
  • Rates of overweight adults remained fairly steady.
Table 1: Rates of overweight and obesity among Australian adults, based on BMI calculated from measured height and weight (per cent)
1995 2007–08
Males
Overweight (but not obese) 45.9 42.5
Obese 18.9 25.2
Overweight or obese 64.8 67.7
Females
Overweight (but not obese) 30.3 30.9
Obese 19.0 23.4
Overweight or obese 49.4 54.3
Persons
Overweight (but not obese) 38.2 36.7
Obese 19.0 24.3
Overweight or obese 57.2 61.1

Notes
1. Directly age-standardised to the 2001 Australian population aged 18 years and over.
2. Includes only those of whom body mass index (BMI) was known.
3. Based on measured data.

Sources: AIHW analysis of ABS NHS 1995 and 2007–08 (reissue).

Self-reported BMI

In Australia in 2007–08:

  • 55% of adults were overweight or obese, based on their self-reported BMI (Table 2).
  • 21% of adults were obese.
  • Males were more likely to be overweight or obese than females.

In the 18 years from 1989–90 to 2007–08:

  • Rates of overweight or obesity among adults rose from 39% to 55%.
  • Obesity rates more than doubled for men and almost doubled for women.

Table 2: Rates of overweight and obesity among Australian adults, based on BMI calculated from self-reported height and weight (per cent)
1989–90 1995 2001 2004–05 2007–08
Men
Overweight (but not obese) 37.3 40.4 42.0 42.8 40.8
Obese 8.5 11.6 15.5 18.8 21.9
Overweight or obese 45.8 52.0 57.5 61.6 62.7
Women
Overweight (but not obese) 22.5 25.0 25.3 27.8 27.7
Obese 9.9 12.3 16.9 16.8 19.9
Overweight or obese 32.3 37.3 42.2 44.7 47.6
Persons
Overweight (but not obese) 29.9 32.8 33.7 35.4 34.4
Obese 9.2 12.0 16.3 17.9 20.9
Overweight or obese 39.1 44.8 49.9 53.3 55.4

Notes
1. Directly age-standardised to the 2001 Australian population aged 18 years and over.
2. Includes only those of whom body mass index (BMI) was known.
3. Based on self-reported data.
4. Note that measured data collected by the 2007–08 NHS indicated the underlying rate of overweight and obesity is slightly higher.
5. Data presented for 1989–90 are for persons aged 20 years or more whereas the data for other years are for persons aged 18 years or more.

Sources: AIHW 2011 analysis of ABS NHS 1989–90, 1995, 2001, 2004–05 and 2007–08 (reissue).

What are the data sources?

There are two main data sources:

  • The 1989–90, 1995, 2001, 2004–05 and 2007–08 (reissue) Australian Bureau of Statistics (ABS) National Health Survey (NHS) (ABS cat. no. 4634.0), and
  • The 2001 Estimated Resident Population (ERP).

How is this indicator calculated?

These rates are directly age-standardised using the 2001 ABS ERP and compare:

  • numerator: the number of adults who are overweight (but not obese), obese, and obese or overweight (from the NHS), to
  • denominator: the total adult population.

Are there any data limitations?

  • AIHW recommends that measured height and weight data be used to monitor indicators of body mass in the population where such data are available (AIHW 2007). BMI is not accurately determined using self-reported information as people tend to overestimate their height and underestimate their weight (AIHW 2007). Therefore, use of self-reported BMI data may underestimate the true prevalence rates of overweight and obesity.
  • Data on measured height and weight for adults are only available for 1995 and 2007–08.
  • The World Health Organization BMI classification is only suitable for people aged 18 years and over (WHO 2000).

Definitions

Adults are people aged 18 years and over, with the exception of the NHS 1989–90, for which 'adults' were classified as 20 years and over.

Body Mass Index (BMI) is calculated by dividing a person's weight in kilograms by the square of their height in metres (kg/m2) (AIHW 2010). The standard classification of BMI recommended by the World Health Organization (WHO) for adults is based on the association between BMI and illness and mortality (WHO 2000):

  • underweight: BMI < 18.5
  • healthy weight: BMI ≥ 18.5 and BMI < 25
  • overweight but not obese: BMI ≥ 25 and BMI < 30
  • obese: BMI ≥ 30.

Where can I find more information?

AIHW (Australian Institute of Health and Welfare) 2011. Risk factors: overweight and obesity. www.aihw.gov.au/risk-factors-overweight-obesity/

AIHW (Australian Institute of Health and Welfare) 2010. Australia’s health 2010. Australia’s health series no. 12. Cat. no. AUS 122. Canberra: AIHW.

AIHW 2007. National indicators for monitoring diabetes: report of the Diabetes Indicators Review Subcommittee of the National Diabetes Data Working Group. Diabetes series no. 6. Cat. no. CVD 38. Canberra: AIHW.

WHO (World Health Organization) 2000. Obesity: preventing and managing the global epidemic. Report of a WHO Consultation. WHO Technical Report Series 894. Geneva: WHO.

Abbreviations

ABS
Australian Bureau of Statistics
AIHW
Australian Institute of Health and Welfare
BMI
Body Mass Index
ERP
Estimated Resident Population
NHS
National Health Survey
WHO
World Health Organisation