Overweight and obesity – adults | National Cancer Control Indicators

Published

22 Nov, 2017

Being overweight or obese is a risk factor for colorectal, breast (post-menopause), oesophageal (adenocarcinoma), endometrial, pancreatic, liver and kidney cancers.^{1, 2} The estimated percentage of cancers attributable to overweight and obesity ranges from 4.5% of cancer cases in Europe³ to 20% in the United States.⁴ It is estimated that 3.6% of all new cancers in adults worldwide are attributable to excess bodyweight.⁵

As the analysis for this measure shows, overweight and obesity is an important cancer control measure to monitor due to the significant variations between population groups at the national level (e.g. sex, area of residential remoteness etc.).

Summary

More than 11 million adults are overweight or obeseIn 2014-15, 11.2 million Australian adults (63.4%) were overweight (6.3 million) or obese (4.9 million).

Nearly one in 10 Australians are morbidly obeseIn 2014-15, 1.7 million Australian adults (9.5%) were morbidly obese (BMI score of 35 or greater).

Obesity is more prevalent  in areas of lower socioeconomic statusIn 2014-15, people living in areas of lower socioeconomic status were 1.6 times more likely to be obese than those living in the highest socioeconomic areas.

Australian obesity rates are among the highest in the developed worldAustralia has a comparatively high prevalence of obesity in a global context – ranking 8th highest (28.1%) among 17 Organization for Economic Cooperation and Development (OECD) countries with measured BMI data.

Data

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Total overweight or obese/Overweight/Obese

Notes

• Data sourced from ABS National Health Survey.
• Error bars indicate 95% confidence intervals.
• Imputation was used to obtain height, weight and BMI scores for 26.8% of respondents (See 'About the data').

Crude rates
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• Data sourced from ABS National Nutrition Survey, Australian Health Survey – Core Content, and National Health Survey.
• Error bars indicate 95% confidence intervals.
• Proportions have been age standardised to the 2001 Australian population.

Proportion of overweight or obese adults by sex, 1995 to 2014-15 (age-standardised)
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• Data sourced from ABS National Nutrition Survey, Australian Health Survey – Core Content and National Health Survey.
• Error bars indicate 95% confidence intervals.

Proportion of overweight or obese adults by age and sex, 1995 to 2014-15
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Notes

• Data sourced from ABS Australian Health Survey – Core Content and Australian Aboriginal and Torres Strait Islander Health Survey – Core Content.
• Error bars indicate 95% confidence intervals.
• Proportions have been age standardised to the 2001 Australian population.

Crude rate and age-standardised rates
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Notes

• Data sourced from ABS Australian Health Survey - Core Content and National Health Survey.
• Remoteness was classified according to the Australian Statistical Geography Standard (ASGS) Remoteness Areas, see 'About the data' for more details.
• Error bars indicate 95% confidence intervals.
• Proportions have been age standardised to the 2001 Australian population.

Age-standardised
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Total overweight or obese/Overweight/Obese
Sex

Notes

• Data sourced from ABS Australian Health Survey – Core Content and National Health Survey.
• SES was classified according to the Socio-Economic Indexes for Areas (SEIFA) Index of Relative Socio-economic Disadvantage (IRSD), see 'About the data' for more details.
• Error bars indicate 95% confidence intervals.
• Proportions have been age standardised to the 2001 Australian population.

Age-standardised rates
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Notes

• Data sourced from OECD.Stat. Health Statistics.
• Caution should be applied as most recent year varies between 2011 and 2017.
• Estimated rate was used for New Zealand
• Different methodology was used for Canada

Proportion of people aged 15 years and over who were obese, 2011 to 2017

About this measure

Overweight and obesity is calculated using the Body Mass Index (BMI), a scale based on height and weight commonly used to define if a person is underweight, normal weight, overweight or obese.^6-8 BMI is calculated by dividing a person’s weight (in kilograms) by their height (in meters). Guidelines established by the World Health Organisation⁸ and the National Health and Medical Research Council⁷ place adults aged 18 years and older into the following categories based on their BMI.

Table 1: Classifications of BMI for adults aged 18 years and over

BMI (kg/m²⁾	Classification
Less than 18.5	Underweight
18.5 to less than 25	Normal weight
25 to less than 30	Overweight
30 or more	Obese
35 or more	Morbidly obese

Where relevant, rates were age-standardised for this measure to account for differences in age structure over time. Age-standardisation was also applied for comparisons between population groups, including: Indigenous and non-Indigenous status, area of residential remoteness, and level of socioeconomic disadvantage.

Current status

In 2014-15, an estimated 11.2 million Australian adults (63.4% of adult population) aged 18 years and over were overweight (35.5%) or obese (27.9%), with the prevalence being higher among males than females (70.8% compared with 56.3%).⁹ This can be attributed to a higher proportion of males being overweight compared with females (42.4% compared with 28.8%) while the obesity rates were similar for both sexes.

The prevalence of adults being overweight or obese increased with age, peaking at 55-64 years for males (81.8%) and at 65-74 years for females (68.8%), before decreasing to 73.2% of males and 65.3% of females aged 75 years and over.⁹ The proportion of overweight and obese males was significantly higher than for females across all age groups. The greatest difference between males and females in the proportion of overweight or obese was observed among age groups 25-34 (20.0 percentage points) and 45-54 years (17.9 percentage points).

Morbidly obese

In 2014-15, nearly one in ten Australian adults (9.5%) had a BMI score of 35 or more, putting them in the morbidly obese category.^9, 10 This corresponded to 1 in every 3 obese people being morbidly obese. Females were more likely to be morbidly obese than males (10.9% compared with 8.2%, respectively).

The proportion of people who were morbidly obese generally increased from age group 25-34 years, peaking at 55-64 years for both males (11.9%) and females (16.2%).^{9, 10} Thereafter, rates reduced by more than half, to 6.0% among females aged 75 years and over whereas a non-significant decline was observed for males aged 75 years and over (8.5%).

Aboriginal and Torres Strait Islander peoples

In 2012-13, 69.2% of Aboriginal and Torres Strait Islander peoples were overweight (29.4%) or obese (39.8%).¹¹ Although the combined overweight and obesity rates were similar between males and females, obesity was more common among females than males (43.3% compared with 36.2%) while overweight rates were higher among males than females (32.3% compared with 26.6%).

The proportion of overweight or obese Aboriginal and Torres Strait Islander peoples generally increased with age, reaching a maximum of 79.6% among those aged 55 years and over.¹¹ While the overweight rates were similar across all age groups, the proportion of obese adults steadily increased with age.

After adjusting for differences in age structure for both Indigenous and non-Indigenous populations, Indigenous Australians were 1.2 times more likely to be overweight or obese than non-Indigenous Australians (72.4% compared with 62.6%).¹¹ Indigenous Australians were 1.6 times as likely as non-Indigenous Australians to be obese (rate ratio 1.4 for males and 1.7 for females). Indigenous males and females had higher rates of obesity in almost every age group when compared with their non-Indigenous counterparts.

Remoteness and socioeconomic status (SES)

The proportion of adults who were overweight or obese in 2014-15 varied considerably according to geographic regions and levels of socioeconomic disadvantage. After adjusting for differences in age structure, adults in Inner Regional (67.1%), and Outer Regional and Remote areas (67.9%) were more likely to be overweight or obese than those in Major cities (61.1%).^{9, 10} This was mainly due to higher rates of obesity among both males and females living in Inner Regional (32.6% for males and 32.3% for females), and Outer Regional and Remote areas (39.6% for males and 34.6% for females) compared with those living in Major cities (25.4% for males and 24.8% for females).

In 2014-15, a higher proportion of people living in lowest SES areas were overweight or obese compared with those living in the highest SES areas (65.3% compared with 57.4%).^{9, 10} The social gradient of obesity showed that proportionally people living in lowest SES areas were 1.6 times more likely to be obese than those living in the highest SES areas (32.9% compared with 20.7%, respectively).¹⁰

Trends

Although the proportion of overweight or obese adults increased from 1995 to 2011-12, there has been no significant change in recent years.^{9, 10, 12-16}After adjusting for differences in age structure over time, the proportion of overweight or obese adults increased from 57.2% in 1995 to 61.1% in 2007-08 and 62.7% in 2011-12. This change was largely as a result of an increase in levels of obesity, from 18.9% in 1995 to 27.3% in 2011-12 for males and from 19.1% in 1995 to 27.1% in 2011-12 for females. This increase can be observed across almost every age group. By comparison, the proportion of overweight adults steadily decreased, from 38.1% in 1995 to 35.5% in 2011-12.

Between 2011-12 and 2014-15, the proportions of overweight or obese adults were similar. ^{9, 14} This was the case for both males and females across all age groups.¹⁶

Remoteness and socioeconomic status (SES)

After adjusting for differences in age structure, the proportion of overweight or obese adults remained unchanged between 2011-12 and 2014-15 across different geographic regions of Australia.^{9, 10} However, among males living in Outer Regional and Remote areas, there was a significant increase in proportion of people who were obese (from 30.0% in 2011-12 to 39.6% in 2014-15) while at the same time a significant decrease in proportion of people who were overweight (from 44.0% in 2011-12 to 34.3% in 2014-15).

This shift in distribution of BMI reflected increases in weight among overweight males in Outer Regional and Remote areas, putting them into the obese category during this time period. Between 2011-12 and 2014-15, males in Outer Regional and Remote areas gained an average 3.5 kg compared with 0.4 kg amongst the general population.^{10, 15} For females, there were no significant changes in proportion of people who were overweight or obese across different geographic regions of Australia.

The age-standardised rates of overweight and obesity were similar across different SES areas between 2011-12 and 2014-15.^{9, 10}

International Comparison (15 years and over)

The growing prevalence of overweight and obesity is a major public health concern worldwide.¹⁷ The latest results showed that more than half of adults aged 15 years and over in Organization of Economic Cooperation and Development (OECD) countries are overweight or obese (57.5%).¹⁷ Australia has comparatively high prevalence of obesity in a global context – ranking 8th highest (27.9%) among 17 OECD countries with measured BMI data.

About the data

This measure shows the proportions of people who were overweight or obese.

Numerator: Number of persons aged 18 years and over who were overweight or obese (i.e. BMI score of 25 or greater).

Denominator: Number of persons aged 18 years and over having their height and weight measured

In the 2011 Index of Relative Socio-Economic Disadvantage, attributes summarised by this index include low income, low educational attainment, high unemployment and jobs in relatively unskilled occupations. A lower Index of Disadvantage quintile (e.g. the first quintile) indicates an area with relatively greater disadvantage and a lack of advantage in general. A higher Index of Disadvantage (e.g. the fifth quintile) indicates an area with a relative lack of disadvantage and greater advantage in general.

BMI score: overweight = 25 to less than 30; obese = 30 or greater; morbidly obese = 35 or greater.

Methodology

Proportions have been age standardised to the 2001 Australian population to account for differences in age structures between the populations.

The 2011-12 NHS data in TableBuilder and 2014-15 NHS data have been randomly adjusted to avoid the release of confidential data. Discrepancies may occur between sums of the component items and totals.

Remoteness

The Australian Statistical Geography Standard (ASGS), was used to allocate participants to a remoteness area based on their area of usual residence.

Earlier data used the now superceeded Australian Standard Geographical Classification (ASGC), 2011-2012 data used the 2006 ASGC and 2014-2015 data used the 2011 ASGC .

Socioeconomic status

The Socio-Economic Indexes for Areas (SEIFA) Index of Relative Socio-Economic Disadvantage (IRSD) was used to allocate participants to a SEIFA quintile based on their usual residence (For 2011-2012 and 2014-2015 data the 2011 IRSD was used).

Data sources

ABS 1995 National Nutrition Survey
ABS 2011-12 Australian Health Survey – Core Content
ABS 2012-13 Australian Aboriginal and Torres Strait Islander Health Survey – Core Content
ABS 2007-08 and 2014-15 National Health Survey
OECD.Stat. Health Statistics (database). Non-medical determinants of health. OECD; 2018. http://stats.oecd.org/index.aspx?DataSetCode=HEALTH_STAT#

Data caveats

Although BMI is correlated with body fat, it does not measure body fat directly or the distribution of body fat.⁶ Therefore, two individuals with the same BMI can have very different patterns of body fat distribution which contributes to different levels of risk of developing chronic diseases. However, BMI is a simple tool in measuring and monitoring trends in overweight and obesity across different populations.

The calculation of BMI is based on measured height and weight data collected from the Australian Bureau Statistics 1995 National Nutrition Survey, 2011-12 Australian Health Survey – Core Content, 2012-13 Australian Aboriginal and Torres Strait Islander and 2007-08 and 2014-15 National Health Survey.^9-15

Table 2 presents the proportions of persons aged 18 years and over who did not have their height and/or weight measured across the survey years:

Survey Year	Height and/or weight not measured (%)
1995	N/A
2007-08	28.6
2011-12	15.8
2012-13	15.0
2014-15	26.8*

_{* For these respondents, imputation was used to obtain height, weight and BMI scores.}

International comparisons

International comparisons were based on persons aged 15 years and over using d measured data. The most recent year for international data varies between 2011 and 2017. Data sourced from OECD.Stat. Health Statistics as at 1 August 2018.

The most recent year for data available by country is as follows:

Country	Most recent year
New Zealand	2017
Ireland	2017
Turkey	2017
United States	2016
Mexico	2016
United Kingdom	2016
Chile	2016
Korea	2016
Japan	2016
Canada	2015
France	2015
Hungary	2014
Australia	2014
Luxembourg	2014
Belgium	2014
Germany	2012
Finland	2011

Estimated rate was used for New Zealand
Different methodology was used for Canada

References

Activity in this area

Data:

Australian Bureau of Statistics. 4364.00.55.001 – National Health Survey, 2014-15. Canberra: ABS; 2015 [Accessed September 2016]; Available at: http://www.abs.gov.au/ausstats/abs@.nsf/PrimaryMainFeatures/4364.0.55.001?OpenDocument

Australian Bureau of Statistics. 4727.0.55.001 – Australian Aboriginal and Torres Strait Islander Health Survey: Updated Results, Australia, 2012-13. Canberra: ABS; 2014; [Accessed September 2016]; Available at: http://www.abs.gov.au/ausstats/abs@.nsf/Lookup/4727.0.55.001main+features12012-13

Social Health Atlases of Australia: Population Health areas – Health risk factors, data; [Accessed October 2017]; Available at: http://phidu.torrens.edu.au/current/maps/sha-aust/pha-single-map/atlas.html

Policy:

National Health and Medical Research Council. Clinical Practice Guidelines for the Management of Overweight and Obesity in Adults, Adolescents and Children in Australia (2013). NHMRC: Canberra; 2013; [Accessed September 2016]; Available at: https://www.nhmrc.gov.au/guidelines-publications/n57

References

1. Cancer Australia. Lifestyle risk factors and the primary prevention of cancer. Sydney: Cancer Australia; 2015 [Accessed September 2016]; Available at: http://canceraustralia.gov.au/publications-and-resources/position-statements/lifestyle-risk-factors-and-primary-prevention-cancer.

2. World Cancer Research Fund/American Institute for Cancer Research. Food, nutrition, physical activity, and the prevention of cancer: a global perspective. Washington, DC: American Institute for Cancer Research; 2007.

3. Stewart BW. Priorities for cancer prevention: lifestyle choices versus unavoidable exposures. The Lancet Oncology. 2012;13(3):e126-33. Epub 2012/03/03.

4. Colditz GA, Wolin KY, Gehlert S. Applying what we know to accelerate cancer prevention. Sci Transl Med. 2012;4(127):127rv4.

5. Arnold M, Pandeya N, Byrnes G, Renehan AG, Stevens GA, Ezzati M, et al. Global burden of cancer attributable to high body-mass index in 2012: a population-based study. The Lancet Oncology. 2015;16(1):36-46. Epub 2014/12/04.

6. Center for Disease Control. Body Mass Index: Considerations for Practitioners. Atlanta, GA: Department of Health; 2015 [Accessed September 2016]; Available at: http://www.cdc.gov/obesity/downloads/bmiforpactitioners.pdf.

7. National Health and Medical Research Council. Clinical Practice Guidelines for the Management of Overweight and Obesity in Adults, Adolescents and Children in Australia. Canberra: NHMRC; 2015 [Accessed September 2016]; Available at: https://www.nhmrc.gov.au/_files_nhmrc/publications/attachments/n57_obesity_guidelines_140630.pdf.

8. World Health Organization. Obesity and overweight. Geneva: WHO; 2016 [Accessed September 2016]; Available at: http://www.who.int/mediacentre/factsheets/fs311/en/.

9. Australian Bureau of Statistics. 4364.0.55.001 - National Health Survey: First Results, 2014-15. Canberra: ABS; 2015 [Accessed September 2016]; Available at: http://www.abs.gov.au/ausstats/abs@.nsf/PrimaryMainFeatures/4364.0.55.001?OpenDocument.

10. 4324.0.55.001 - Microdata: National Health Survey, 2014-15 [database on the Internet]. ABS. 2016 [Accessed September 2016].

11. Australian Bureau of Statistics. 4727.0.55.006 - Australian Aboriginal and Torres Strait Islander Health Survey: Updated Results, 2012–13. Canberra: ABS; 2014 [Accessed September 2016]; Available at: http://www.abs.gov.au/ausstats/abs@.nsf/Lookup/4727.0.55.006main+features12012-13.

12. Australian Bureau of Statistics. 4805.0 - National Nutrition Survey: Nutrient Intakes and Physical Measurements, Australia, 1995. Canberra: ABS; 1998 [Accessed September 2016]; Available at: http://www.abs.gov.au/AUSSTATS/abs@.nsf/Lookup/4805.0Main+Features11995?OpenDocument.

13. Australian Bureau of Statistics. 4362.0 - National Health Survey: Summary of Results, 2007-2008 (Reissue) Canberra: ABS; 2009 [Accessed September 2016]; Available at: http://www.abs.gov.au/AUSSTATS/abs@.nsf/Latestproducts/4364.0History%20of%20Changes02007-2008%20(Reissue)?opendocument&tabname=Summary&prodno=4364.0&issue=2007-2008%20(Reissue)&num=&view=.

14. Australian Bureau of Statistics. 4364.0.55.003 - Australian Health Survey: Updated Results, 2011-2012. Canberra: ABS; 2013 [Accessed September 2016]; Available at: http://www.abs.gov.au/ausstats/abs@.nsf/Lookup/4364.0.55.003main+features12011-2012.

15. 4324.0.55.003 - Microdata: Australian Health Survey, Core Content - Risk Factors and Selected Health Conditions, 2011-12 [database on the Internet]. ABS. 2014 [Accessed September 2016]. Available at: http://www.abs.gov.au/ausstats/abs@.nsf/Lookup/4324.0.55.003main+features12011-12.

16. Australian Bureau of Statistics. 4125.0 - Gender Indicators, Australia, August 2016. Canberra: ABS; 2016 [Accessed September 2016]; Available at: http://www.abs.gov.au/ausstats/abs@.nsf/mf/4125.0.

17. Organization for Economic Cooperation and Development. "Obesity among adults", in Health at a Glance 2015: OECD Indicators. Paris: OECD Publishing; 2015 [Accessed September 2016]; Available at: https://www.oecd-ilibrary.org/social-issues-migration-health/health-at-a-glance-2015/obesity-among-adults_health_glance-2015-19-en

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Summary

More than 11 million adults are overweight or obese

Nearly one in 10 Australians are morbidly obese

Obesity is more prevalent in areas of lower socioeconomic status

Australian obesity rates are among the highest in the developed world

Data