Obesity

This policy focuses on public policy interventions to reduce the impact of cancers attributable to the individual and interacting effects of obesity, poor nutrition and physical inactivity and supporting evidence. It will be updated as significant new literature is published or changes in the policy environment occur.

This policy has been developed by Cancer Council Australia and the Nutrition, Alcohol and Physical Activity Expert Committee, and endorsed by Cancer Council’s principal Public Health Committee. This policy was published in 2022.

Please contact cancercontrolpolicy@cancer.org.au to be updated on when the revised policy will be available or if you have any questions.

Key policy priorities in summary

• Implement actions under the National Obesity Strategy and the National Preventive Health Strategy
• Create environments that support healthy eating:
  • Develop and implement a National Nutrition Policy Framework to identify, prioritise, drive and monitor healthy eating in Australia
  • Mandate the Health Star Rating System to support healthy food options
  • Implement government regulation to protect children from the marketing of unhealthy foods and drinks
  • Introduce a 20% health levy on sugar sweetened beverages
  • Develop a nationally consistent standard for kilojoule labelling on menu boards
• Create environments that support physical activity
  • Develop a national physical activity plan
• Support Australians to avoid excess weight gain through a social marketing campaign encouraging healthy eating and physical activity behaviours.
  

Collectively, the independent risk factors of overweight and obesity, physical inactivity, and inadequate diet are second only to tobacco as modifiable risk factors for cancer^{(1, 2)}. Healthy eating and physical activity protect against certain cancers both directly, and indirectly, through their impact on body weight.

Addressing these risk factors is an important objective for reducing Australia’s cancer burden given obesity and overweight have reached record levels in the Australian population. Two in three (67%) Australians aged 18 years and over have a body mass index (BMI) classified as overweight or obese ⁽³⁾ and one in four (25%) Australian children have overweight or obesity. ⁽³⁾

The World Cancer Research Fund (WCRF) systematically reviews global evidence on diet, weight, and physical activity in relation to cancer risk according to levels of evidence. The grading criteria used by WCRF provides a systematic way to judge how strong any evidence of causality is. Evidence is categorised as being ‘strong’ (‘convincing’, ‘probable’ or ‘substantial effect on risk unlikely’) or ‘limited’ (‘limited – suggestive’ or ‘limited – no conclusion’). There is convincing evidence that overweight and obesity increase the risk of cancers of the oesophagus, pancreas, bowel, breast (post-menopausal), endometrium, kidney and liver. ⁽²⁾ Furthermore, there is probable evidence that overweight and obesity increase the risk of cancers of mouth, pharynx, larynx, ovary, prostate, gallbladder and stomach. ⁽²⁾ Physical activity has been shown to convincingly protect against bowel cancer and probably protect against breast (post-menopausal) and endometrium cancers. ⁽²⁾ Dietary factors such as limiting red and processed meat, and eating enough foods containing dietary fibre (e.g. fruit, vegetables, legumes and wholegrains) probably protect against cancers of the bowel. ⁽²⁾ Further to this, the International Agency for Research on Cancer (IARC) has shown there is sufficient evidence that high body mass increases the risk of 13 types of cancer. ⁽⁴⁾ In summary then, there is strong evidence that overweight and obesity are factors associated with developing cancer.

In 2018, the Australian Institute for Health and Welfare found 7.0% of total cancer burden (number of years of life lost due to cancer-related death or spent living in ill health or with disability) was attributable to high body mass, 4.5% of the total cancer burden as due to dietary factors and 1.8% due to physical inactivity. ⁽⁵⁾ A 2017 study ⁽¹⁾ quantified the number of cancer cases attributable to modifiable factors in Australia, and found that 4.3% of cancers in 2013 were attributable to overweight/obesity and 1.5% of cancers were due to insufficient physical activity. Dietary factors were attributable for 9.8% of cancers which incorporated inadequate fruit, vegetables and fibre intake and high consumption of red and processed meat consumption accounting for 18% of bowel cancers diagnosed in Australians in 2013. Further information about the evidence linking diet, physical activity and weight with cancer risk can be found in other parts of this chapter: Links between cancer and weight, nutrition and physical activity

As well as being a direct cause of several cancers⁽²⁾⁽⁶⁾, alcohol consumption may indirectly increase cancer risk by contributing to obesity and overweight. For further information on the link between alcohol consumption and cancer risk (not covered in this chapter), see the Alcohol chapter of the National Cancer Control Policy.

Evidence-based healthy eating, physical activity and weight management guidelines for cancer prevention

The WCRF has published recommendations based on its review of evidence on diet, weight, and physical activity in relation to cancer risk. Recommendations include: maintain a healthy weight; move more and sit less; eat wholegrains, fruit, vegetables and legumes; limit fast food and processed foods high in fats, starches and sugars; limit red and processed meat, sugar sweetened drinks and alcohol. Additional recommendations discourage supplement use and encourage breastfeeding.⁽⁷⁾

Similarly, the International Agency for Research on Cancer (IARC) has published the European Code against Cancer which includes recommendations to reduce cancer risk. IARC encourages people to maintain a healthy body weight, be physically active and less sedentary, eat wholegrains, legumes, vegetables and fruit, limit energy dense foods high in sugar or fat, avoid sugary drinks, limit red meat and avoid processed meats, and limit alcohol or avoid alcohol altogether.⁽⁸⁾

The guidelines developed by the Australian Government on body weight, physical activity and healthy eating are consistent with WCRF and IARC recommendations to reduce cancer risk and are endorsed by Cancer Council Australia.

The Australian Dietary Guidelines provide evidence-based recommendations on types and amounts of foods, food groups and dietary patterns to promote health and reduce the risk of chronic disease.⁽⁹⁾ The guidelines include specific dietary advice for pregnant and breastfeeding women, infants, children and adolescents, adults and older Australians. These guidelines recommend healthy eating patterns that are consistent with cancer prevention. and should be the foundation of all food and nutrition policy and regulation in Australia.

Australia’s Physical Activity and Sedentary Behaviour Guidelines for children, young people, adults and older Australians provide evidence-based recommendations on minimum levels of physical activity required to gain a health benefit, as well how to minimise sedentary behaviour to reduce the risk of chronic disease and obesity. ⁽¹⁰⁾

The Clinical Practice Guidelines for the Management of Overweight and Obesity in Adults, Adolescents and Children in Australia (rescinded) provided evidence-based guidelines to clinicians regarding the management of individuals who have a BMI greater than 25.⁽¹¹⁾ New Clinical Practice Guidelines have not been developed, and there is no indication when NHMRC will undertake that work. .

These guidelines should be the foundation of all cancer prevention, food, nutrition and physical activity policy and regulation in Australia.

This section of Cancer Council Australia’s National Cancer Control Policy Obesity Chapter discusses: the public policy context and effective policy interventions that can reduce the prevalence of these cancer risk factors. The chapter also summarises Cancer Council Australia’s recommended, evidence-based policy priorities for reducing the cancer burden in Australia attributable to obesity and overweight, physical inactivity and inadequate diet. The impact in Australia of cancers related to obesity and overweight, physical inactivity, and inadequate diet and evidence on the links between these factors and cancer are also covered.