What is causing the rapid rise in overweight and obesity in Australia and around the world?

The prevalence of overweight and obesity is increasing at an alarming rate in all regions of the world leading to what has been referred to as an ‘epidemic’ of overweight and obesity. In the past 20 years, the proportion of Australians who are overweight or obese has increased substantially.

So, what is causing so many of us to put on weight?  We put on weight when the energy (calories of kilojoules) we consume in food exceeds the energy we expend in activity and bodily processes.  However, the causes of this energy imbalance are not completely understood, and scientific research is attempting to provide an answer to this question. There are many factors - biological, behavioural, social, genetic and environmental – which contribute to increased food intake or reduced energy expenditure and have been associated with weight gain. High-fat/sugar, energy-dense diets and sedentary lifestyles are two major factors that are most strongly associated with the increased prevalence of obesity worldwide. Fat contains more energy (calories or kilojoules) by weight that does carbohydrate and protein, therefore making weight gain more likely as energy intake is increased greatly in high fat diets. High sugar foods can also be very energy dense and usually do not contain the fibre and nutrients of low energy dense foods such vegetables and fruit. Regular consumption of high-fat and high sugar foods and drinks such as take away foods, salty packet snacks, confectionery and soft drink can often lead to an intake of excess calories which the body stores as fat.  The ability for the body to store fat is virtually unlimited.

Modern technology and changes in lifestyle have created a society where people are becoming less physically active and increasingly sedentary. Research has often revealed that obese and overweight people are less active and in particular, spend more time in sedentary leisure time pursuits such as TV watching and computer use, than those who are lean.  Results of numerous studies suggest that low or decreasing levels of physical activity are an important factor in weight gain and the trend in the increased prevalence of obesity seems to parallel a decrease in physical activity and an increase in sedentary behaviour.