ACTGHS BMI underweight, adults

Commentary

Body Mass Index (BMI) is a simple index of weight-for-height that is commonly used to classify underweight, healthy weight, overweight and obesity.

BMI for adults aged 18 years and over are grouped as follows:

Underweight: BMI less than 18.5
Healthy weight: BMI 18.5 - 24.99
Overweight: BMI 25.00 - 29.99
Obese class 1: BMI 30.00 -  34.99
Obese class 2: BMI 35.00 - 39.99
Obese class 3: BMI 40 or more

Source: 4363.0 - National Health Survey: Users' Guide, 2017-18

1.7% of respondents to the 2021 ACT General Health Survey aged 18 years and over were classified as being underweight.

BMI is based on self-reported height and weight. To calculate BMI, weight in kilograms was divided by the square of height in metres.

For the purpose of reporting the ACT General Health Survey data on HealthStats, if the 95% confidence intervals of the estimates do not overlap, they are considered to be significantly different.

Note: The indicator shows self-reported data collected through Computer Assisted Telephone Interviewing (CATI). Estimates were weighted to adjust for differences in the probability of selection among respondents and were benchmarked to the estimated residential population using the latest available Australian Bureau of Statistics population estimates.

Data for BMI are not collected every third year (i.e. 2019 and 2022).

Persons includes male, female, other and refused sex respondents and may not always add to the sum of male and female.

The following estimates have a relative standard error of 25% to 50% and should be used with caution:

• 2011/12: underweight males and females
• 2013/14: underweight males and females
• 2015/16: underweight females
• 2018: underweight persons and females
• 2020: underweight persons
• 2021: underweight persons and females.

The following estimates have not been published due to small numbers or a relative standard error greater than 50%:

• 2015/16: underweight males
• 2018: underweight males
• 2020: underweight males and females
• 2021: underweight males.

Statistically significant differences are difficult to detect for smaller jurisdictions such as the Australian Capital Territory. Sometimes, even large apparent differences may not be statistically significant. This is particularly the case in breakdowns of small populations because the small sample size means that there is not enough power to identify even large differences as statistically significant.

Chart

Proportion of adults aged 18 years and over whose Body Mass Index was underweight, ACT General Health Survey, 2011-2021

Data

To access the data, select "View source data" link at the bottom of the visualisation. This link will open up a data table that you can download.

Codes and sources

Q. How tall are you without shoes?
Q. How much do you weight without clothes or shoes?

Don't know and refused responses were excluded from analysis.

A copy of the ACT General Health Survey questionnaires can be found in Data collections.