and the link between overweight and obesity


What is overweight and obesity?

Overweight and obese are terms used to describe the body weight of people who are carrying excess body fat. To determine whether someone is overweight or obese, their body mass index (BMI) is calculated using their height and weight.

Becoming overweight or obese happens gradually as a result of either;

  • consuming more energy (kilojoules from food and drinks) than your body needs;
  • consuming more energy (kilojoules from food and drinks) than your body uses by being active;
  • a combination of both.

Overweight and obesity is harmful to health as it increases a person's risk of developing chronic diseases including cardiovascular disease, type 2 diabetes and some cancers. It also increases their risk of developing other health issues, including high blood pressure, gall bladder disease, fertility problems, lower back pain and sleep apnoea.

The more excess weight a person is carrying, the higher their risk of health issues.

Want to find out if you are in the healthy weight range? Learn more at

What is cancer?

Cancer is a disease of the body's cells. The body is constantly making new cells to replace worn-out ones, to grow, or to heal itself after an injury.

Normally cells grow and reproduce themselves in an orderly way. Sometimes, cells can reproduce themselves in an uncontrolled way, which can lead to cancer. These cancer cells can form a tumour, damage the surrounding area and spread to other areas of the body.

It is important to understand that cancer is not a single disease with a single cause, effect or treatment.

Cancer is a leading cause of death in Australia, accounting for 3 in every 10 deaths. In 2011, more than 43,200 Australians died of cancer – that's more than 830 people every week.

What causes cancer?

In many cases the cause of a cancer is unknown. However, there are many things that can increase your risk of developing cancer. Some of these we can't change, like our genes, or our age.

Some things that increase our risk of developing cancer, we can change. These include:

  • Smoking
  • Drinking alcohol
  • UV radiation (sun exposure)
  • Physical inactivity
  • Being overweight or obese

group of people

How is cancer related to overweight and obesity?

Being overweight or obese is a risk factor for developing many kinds of cancer. Research has found that being overweight or obese was associated with developing the following cancers1:

  • Uterus (womb)
  • Gallbladder
  • Kidney
  • Cervix
  • Thyroid
  • Leukaemia
  • Liver
  • Colon
  • Ovarian
  • Breast cancer (in post-menopausal women)

The exact reason why being overweight or obese makes you more likely to develop these cancers is not yet fully understood. It is likely to do with the fact that body fat (especially fat around the waist and vital organs) produces chemicals and hormones that are released into the body. Having an excess of these chemicals and hormones creates an environment in the body that makes cancer more likely to grow2.

Being a healthy weight can reduce your risk of developing these cancers. Eating plenty of vegetables, decreasing your alcohol intake and doing regular physical activity can both decrease your risk of cancer and help you to achieve a healthy weight.

What can I do to reduce my risk of overweight/obesity?

Our weight generally comes down to two factors: how much we eat and drink (energy in) and how active we are (energy out). It is all about achieving a balance. If you are aiming for weight loss, increase energy out (by being physically active) and reduce energy in (by eating healthy food).

To achieve and maintain a healthy weight, the best things you can do are to:

  • Eat a variety of nutritious foods from the Australian Guide to Healthy Eating
  • Limit intake of foods high in saturated fat, added sugar and salt
  • Be physically active every day

For good health and to help you reach your healthy weight goals, we recommend following our top tips to LiveLighter®:

  • Watch your portion size
  • Avoid sugary drinks
  • Sit less
  • Cut back on salt
  • Cut back on alcohol
  • Watch the fats you eat
  • Go for 2 fruit and 5 veg
  • Cut back on added sugar
  • Choose healthy snacks
  • Be active every day

Working to achieve a healthy weight will help to lower your risk of developing chronic disease. However, it is important to note that no matter what your size or weight is, being physically active and eating well will improve your health.

For more information on how to achieve and maintain a healthy weight for good health, visit the following websites:

If you think you are overweight or obese, we encourage you to see your GP or an Accredited Practising Dietitian for personalised advice.

1Bhaskaran, K. et al. Body-mass index and risk of 22 specific cancers: a population- based cohort study of 5·24 million UK adults. Lancet 6736, 1–11 (2014).

2Donohoe, C. L., Doyle, S. L. & Reynolds, J. V. Visceral adiposity, insulin resistance and cancer risk. Diabetol. Metab. Syndr. 3, 12 (2011).