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Overweight and obesity

Overweight and obesity

Introduction

Throughout Australia, the prevalence of overweight and obesity is increasing. Being overweight or obese increases the risk of a wide range of health problems, including cardiovascular disease, type 2 diabetes, breast cancer, gallstones, degenerative joint disease, obstructive sleep apnoea, and impaired psychosocial functioning.[1] Overweight and obesity develop when the energy intake from food and drink exceeds energy expenditure from physical activity and other metabolic processes.

The prevalence of overweight and obesity is calculated using the Body Mass Index (BMI). BMI is calculated by dividing a person's weight (in kilograms) by their height (in metres squared). The resulting BMI is then classified into 4 categories: underweight when the BMI is less than 18.5, acceptable or ideal weight when the BMI is greater than or equal to 18.5 and less than 25, overweight when the BMI is greater than or equal to 25 and less than 30, and obese when the BMI is greater than or equal to 30.[2,3] Although studies have shown self-reported BMI results in an under-estimation of measured BMI, it is still useful for ongoing surveillance of population health.

In 2006, the New South Wales Population Health Survey asked respondents: How tall are you without shoes? and, How much do you weigh without clothes or shoes? These answers were used to estimate body mass index (BMI).

Results

In 2006, according to estimates of BMI based on self-reported height and weight, 2.6 per cent of adults were underweight, 46.9 per cent were healthy weight, 32.7 per cent were overweight, and 17.7 per cent were obese.

Overweight or obese

In 2006, 50.4 per cent of adults were overweight or obese. A significantly higher proportion of males (57.4 per cent) than females (43.3 per cent) were overweight or obese. Among males, a significantly lower proportion of those aged 16-24 years (31.3 per cent) and 75 years and over (48.2 per cent), and a significantly higher proportion aged 45-54 years (66.2 per cent) and 55-64 years (69.5 per cent) and 65-74 years (66.2 per cent), were overweight or obese, compared with the overall adult male population. Among females, a significantly lower proportion of those aged 16-24 years (24.4 per cent), and a significantly higher proportion of those aged 55-64 years (57.2 per cent) and 65-74 years (56.4 per cent), were overweight or obese, compared with the overall adult female population.

A significantly higher proportion of adults in rural areas (52.5 per cent) than urban areas (49.5 per cent) were overweight or obese, compared with the overall adult population. A higher proportion of adults in the Sydney West (55.7 per cent) and Greater Western (56.0 per cent) Health Areas were overweight or obese, compared with the overall adult population. A significantly lower proportion of residents in the Northern Sydney & Central Coast Health Area (44.1 per cent) were overweight or obese, compared with the overall adult population.

A lower proportion of adults in the least disadvantaged quintile (41.1 per cent), and a higher proportion of adults in the third most disadvantaged quintile (55.5 per cent) and most disadvantaged quintile (54.3 per cent), were overweight or obese, compared with the overall adult population.

The proportion of adults who were overweight or obese has risen significantly from 1997 (41.8 per cent) to 2006 (50.4 per cent). This significant increase has occurred in both males (49.3 per cent to 57.4 per cent) and females (34.2 per cent to 43.3 per cent).

Obesity

In 2006, according to estimates of BMI based on self-reported height and weight, 17.7 per cent of adults were obese. There was no significant difference in the proportion of males and females who were obese. A significantly lower proportion of adults aged 16-24 years (9.0 per cent) and 75 years and over (11.0 per cent), and a significantly higher proportion of adults aged 45-54 years (22.8 per cent) and 55-64 years (24.5 per cent), were obese.

There was no significant variation in the proportion of adults who where obese between rural areas and urban areas; however, a lower proportion of adults in the Northern Sydney & Central Coast Health Area (12.5 per cent) were obese, compared with the overall adult population.

Obesity increased with socioeconomic disadvantage. A lower proportion of adults in the least disadvantaged quintile (11.7 per cent), and a higher proportion of adults in the most disadvantaged quintile (22.7 per cent) were obese, compared with the overall adult population.

Overall, the proportion of adults who were obese has increased significantly between 1997 (11.2 per cent) and 2006 (17.7 per cent). This significant increase has occurred in both males (11.0 per cent to 18.9 per cent) and females (11.3 per cent to 17.4 per cent).

References

NSW Centre for Public Health Nutrition. Report on the weight status of New South Wales: 2003. Sydney: NSW Centre for Public Health Nutrition, 2003. Available online at www.cphn.mmb.usyd.edu.au/resources/index.html (accessed 10 May 2007).
Flood V, Webb K, Lazarus R, Pang G. Use of self-report to monitor overweight and obesity in populations: Some issues for consideration. Aust N Z J Public Health 2000; 24: 96-99. Available online at www.phaa.net.au/anzjph/journalpdf_2000/feb_2000/p.%2096-99.pdf (accessed 10 May 2007).
World Health Organization. Obesity: Preventing and managing the global epidemic. Report of a WHO consultation. WHO Technical Report Series 894. Geneva: World Health Organization, 2004 reprint. Available online at http://whqlibdoc.who.int/trs/who_trs_894.pdf (accessed 10 May 2007).

Graphs

Source:	New South Wales Population Health Survey 2006 (HOIST). Centre for Epidemiology and Research, NSW Department of Health.
Print version:	Although this page can be printed directly from your web browser, a higher quality version is available as a PDF file that can be printed or viewed on screen.
Produced by:	Centre for Epidemiology and Research, Population Health Division, NSW Department of Health.
Last updated on:	1 July 2007