In 2017–18, 67% of Australians aged ≥18 years had or were living with overweight or obesity (31% had obesity).¹ One in four children and adolescents aged 2–17 years had overweight or obesity (8.2% had obesity).¹ Genes and the physical and social environment are important risk factors for having overweight and obesity, along with an imbalance between energy intake from the diet and energy expenditure in physical activity and metabolism.

The recommendations in this chapter refer to the prevention of overweight and obesity and should be read in conjunction with nutrition, physical activity and preventive activities in childhood. 

The Australian guidelines, Clinical practice guidelines for the management of overweight and obesity in adults, adolescents and children in Australia, are currently being updated and are due to be released in 2024. 

BMI precautions⁵

• Ethnicity: People with a South Asian, Chinese, other Asian, Middle Eastern, Black African or African Caribbean family background are prone to central adiposity and their cardiometabolic risk occurs at a lower BMI, so use lower BMI thresholds as a practical measure of overweight and obesity:
  • overweight: BMI 23–27.4 kg/m²
  • obesity: BMI ≥27.5 kg/m².

For people in these groups, obesity classes 2 and 3 are usually identified by reducing the thresholds highlighted in Recommendation 1.2.7 of the National Institute for Heath and Care Excellence (NICE) guidance by 2.5 kg/m².

• People with high muscle mass: Interpret BMI with caution in adults with high muscle mass because it may be a less accurate measure of central adiposity in this group.
• People aged ≥65 years: Interpret BMI with caution in people aged ≥65 years, taking into account comorbidities, conditions that may affect functional capacity and the possible protective effect of having a slightly higher BMI when older. 

Waist measurement

Waist measurement in adults with a raised BMI provides a more direct measure of central obesity. 

Table 1. Waist size showing increased risk of chronic disease⁶

Weight stigma and shaming

Clinicians should be aware that patients living with overweight and obesity experience stigma in daily life and in healthcare settings. Consent should be sought sensitively and at appropriate consultations before engaging in anthropometric measurements. The clinical emphasis should be on health and functional gains as a result of weight reduction/improved body composition. 

Extreme diets

Advise against following extreme eating patterns that do not follow healthy eating pattern guidance, as well as programs that focus on short-term weight reduction, because these have poor long-term outcomes.⁵

For specific recommendations for Aboriginal and Torres Strait Islander people, please refer to the Overweight and obesity section in the National guide to a preventive health assessment for Aboriginal and Torres Strait Islander people.

Overweight and obesity rates differ across Australia, being higher in regional and remote areas, and in low socioeconomic groups.¹

Please refer to the Physical activity and Nutrition chapters for relevant recommendations. This section will be reviewed when the updated Australian Clinical practice guidelines for the management of overweight and obesity in adults, adolescents and children in Australia have been released.