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CH-FIT study

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A healthy weight range for adults is commonly determined by body mass index (BMI), a calculation involving an individual’s weight and height. A healthy BMI is considered to be between 20 and 25. A person with a BMI of 25 or more is considered overweight, while a BMI of 30 or more is considered obese.

Two thirds of Australian adults are overweight or obese,
equivalent to 12.5 million people. Almost one quarter of children aged 5–17 years are overweight or obese.1

Obesity is typically caused by an imbalance between the energy taken in through food and the energy burned off through physical activity, ie, eating too much and moving too little. The body needs a certain amount of energy to function, but in an unhealthy lifestyle where more energy than needed is taken in, the surplus energy will be turned into fat.

Some medical conditions, such as an underactive thyroid gland (hypothyroidism) and Cushing’s syndrome, can also cause obesity.

More about BMI

BMI is calculated by dividing a person’s weight (in kilograms) by the square of their height (in metres), ie, kg/m2. While BMI is a useful measurement for most adults, it is only an estimate and does not take into account age, ethnicity or gender, or differentiate between body fat and muscle mass. BMI should be considered alongside waist circumference (which helps to assess risk by measuring the amount of fat carried around an individual’s middle) and other risk factors.

The impact

Obesity and being overweight is a risk factor for various health conditions, such as heart and cardiovascular conditions like stroke, type 2 diabetes, atrial fibrillation, high blood pressure, certain types of cancer, fatty liver disease, kidney disease, sleep apnoea and osteoarthritis.

It can also have an impact during pregnancy, such as high blood pressure (preeclampsia), high blood glucose (gestational diabetes) and increased risk for Caesarean delivery.

A person’s quality of life may also be impacted through obesity stigma. This stigma has been associated with increased depression, anxiety and social isolation.2

The risk

A range of factors can contribute to being overweight or obese.

  • Taking in more energy through food than is used by the body
  • Lack of physical activity
  • A sedentary lifestyle that includes a large amount of sitting during the day, even if an individual is physically active.

Other factors that can contribute include:

  • Genetic factors such as parental overweight or obesity
  • Birth factors such as maternal smoking and poor nutrition
  • Socioeconomic factors such as having lower levels of education and income.

Regular exercise and maintaining a healthy eating plan can help manage the risk of being overweight or obese. HRI has plenty of heart-healthy recipes for inspiration, as well as advice on nutrition and tips for leading a healthy lifestyle.

What is HRI doing?

The Cardiometabolic Disease Group is finding new ways to treat diseases that are increasingly driven by obesity, such as type 2 diabetes. Their discovery of a new molecule that can predict diabetes 12 years before diagnosis has huge potential to facilitate early intervention that can prevent diabetes. This molecule may also help determine if this pathway can treat type 2 diabetes.


  1. Australian Bureau of Statistics, 2017–2018 National Health Survey.
  2. World Health Organization. Weight bias and obesity stigma.

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