What is Obesity?

Obesity has become an international epidemic and emerged as one of the greatest threats to world health of the 21st century, and in Australia overweight and obesity has reached epidemic proportions1.

Statistics prepared by the Australian Bureau of Statistics2 (ABS) show that:

  • 61.3% of people aged 18 years or over are either overweight (BMI 25.00-29.99) or obese (BMI 30+).
  • Only 36% of Australians are considered of ‘normal’ weight (BMI 18.50-24.99) and 2% of people are actually underweight (BMI 18.5 and under).
  • The figures are even higher for some ethnic and age groups.

Obesity can be life threatening

Obesity is not simply carrying a bit of extra body weight. Being obese can lead to life threatening illnesses such as diabetes, cardiovascular disease, joint problems, obstructive sleep apnoea and some cancers1

Researchers have shown that obese people with a Body Mass Index (BMI) of 30-35 may live two to four years less than average3. Those people with a BMI of 40-45 may reduce their life expectancy by eight to ten years, which is comparable to the health risks of smoking3.

Losing weight can greatly improve your general health, your quality of life and your sense of wellbeing. It can also help to prevent or moderate many harmful diseases. 

What are the causes of obesity?

Obesity could be a combination of the following:

  • The genes you inherited from your parents
  • How well your body turns food into energy
  • Your eating and exercising habits
  • Your surroundings
  • Psychological factors. 

How do you know if you are obese?

Obesity is an excess of total body fat, which results from caloric intake that exceeds energy usage.  A measurement used to assess health risks of obesity is BMI.

Click here to find out more about BMI and to measure your own BMI.

Do you want to know more about obesity?

If you want to read more about obesity, please visit other pages on this site, specifically:

Or contact us for more information about any questions you have. 


  1. NHMRC, Clinical Practice Guidelines for the Management of Overweight and Obesity in Adults, National Health and Medical Research Council, Australian Government, Canberra, 2033
  2. Australian Bureau of Statistics, National Health Survey Summary of Results 2007 - 08, Cat Number 4364.0, Australian Government, Canberra, 2009. 
  3. Prospective Studies Collaboration, Body Mass INdex and cause mortality in 900,000 adults: collaborative analysis of 57 Prospective Studies, The Lancet, 2009; 373:1083-96.
© Dr Tony Patiniotis - Hobart Obesity Surgery Centre, Tasmania, Australia