4842.0.55.001 - Overweight and Obesity in Adults in Australia: A Snapshot, 2007–08  
ARCHIVED ISSUE Released at 11:30 AM (CANBERRA TIME) 27/05/2011  First Issue
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Contents >> Data sources and definitions >> Data sources and definitions

Data sources and definitions

This article discusses overweight and obesity of adults in Australia in 2007-08, examining a range of factors which may influence a person's weight, and some of the health consequences associated with excess weight. The article uses measured height and weight data from the 1995 Australian Bureau of Statistics (ABS) National Nutrition Survey (NNS) and the 2007-08 ABS National Health Survey (NHS) to calculate Body Mass Index (BMI) and classify people as underweight, normal weight, overweight and obese. While BMI does not distinguish between weight due to muscle (which is denser and heavier than body fat) and weight due to fat in individuals(footnote 1) , it provides a good population-level measure of overweight and obesity. Measured height and weight data provides a more accurate picture of the nation's overweight and obesity rates compared with self-reported height and weight data, as people tend to over-report their height and under-report their weight when asked to provide an estimate(footnote 2) .

Body Mass Index (BMI)

In this article, overweight and obesity are calculated using BMI, a simple index of weight for height that is commonly used in classifying people as overweight and obese. It is defined as the weight in kilograms divided by the square of the height in metres (kg/m2). To produce a measure of the prevalence of underweight, normal weight, overweight or obesity in adults, BMI values are grouped according to the table below, which allows categories to be reported against both the World Health Organisation (WHO) and, in Australia, the National Health and Medical Research Council guidelines.

      Body Mass Index, Adult
          Underweight: Less than 18.5
          Normal range: 18.5 to less than 25.0
          Overweight: 25.0 to less than 30.0
          Obese: 30.0 and greater

Equivalised household income

Equivalised household income is the total income at the household level adjusted using an equivalence scale to enable analysis of the relative incomes of households of different size and composition. This can be viewed as an indicator of the economic resources available to a standardised household.

Age standardisation

Age standardisation is a way of allowing comparisons between two or more populations with different age structures, in order to remove age as a factor when examining correlations between other variables. For example, the age distribution of people with diabetes is heavily skewed towards the higher age groups (that is, older people are more likely to have diabetes than younger people). When looking at the labour force status of people with and without diabetes, it can be seen that more people with diabetes are not in the labour force, however, this could be due to the fact that there are more older people with diabetes and less older people in the work force. Age standardising removes age from the picture so it can be seen whether there is a correlation between diabetes and labour force status independent of age. This is achieved by applying a single population structure to each of the populations being compared.

In this article, the Australian 2001 estimated resident population is used as the reference population.

1 WHO (World Health Organisation) 2000. Obesity: preventing and managing the global epidemic. Report of a WHO consultation. Technical report series 894. Geneva: WHO <back
2 ABS (Australian Bureau of Statistics) 1998. How Australians measure up. ABS Cat. No. 4359.0. Canberra ABS <back

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