Health Spotlight: Obesity

Overweight and obesity are defined as abnormal or excessive fat accumulation that may impair health. It is commonly measured by body mass index (BMI) which is calculated by dividing a person’s weight in kilograms by height squared. The World Health Organisation recommends a BMI of 18.5 to 24.9.

People with a BMI of greater than or equal to 25 are classified as overweight. Those with a BMI above or equal to 30 are regarded as obese.

Being overweight or obese is a major risk factor for many health-related conditions including heart disease, asthma, kidney disease, dementia, diabetes and some cancers.⁵ It is also a risk factor for a number of mental health conditions including depression, anxiety and dementia.

Unlike other health-related conditions, a diagnosis of obesity or being overweight is straightforward (i.e., BMI calculation). Gaining weight is something most people can detect without jumping on the scales. Gradual, consistent weight gain should be addressed.

Other symptoms may include breathlessness, heart palpitations, high blood pressure or aching joints.

There are many overlapping causes of obesity. In our wider environment, the availability of affordable, healthy food choices, provision of enough open space for leisure/exercise and marketing of foods high in fat, sugar and salt all play a role.

Tied to this, Australians living in regional areas and those in lower socioeconomic groups are at greater risk of being overweight or obese.⁶

At an individual level, genetics and lifestyle are two key factors. Research is providing more insight into the role of genetics including specific genes which are thought to be key markers for obesity. Those with certain medical or psychological conditions may also be more at risk of gaining weight.

Lifestyle factors are more straightforward to understand. For instance, 9 in 10 Australian adults don’t consume the recommended number of serves of vegetables daily, and 5 in 10 don’t eat the recommended amount of fruit.⁷ Almost 3 in 10 adults also do not perform the required amount of physical activity per day.⁸

Our growing reliance on devices and technology is creating more sedentary lifestyles. While emerging evidence suggests the energy in, energy out theory of obesity is probably a bit too simplistic these days, it’s a good place to start.

Losing weight should be applauded but sometimes it can be more difficult to maintain the weight loss. People who’ve lost weight should be careful not to slide back into old habits.

^{1 Australian Government National Obesity Strategy 2022-2023}

^{2 Overweight and obesity among Australian children and adolescents. Australian Institute of Health and Welfare, August 2020}

^{3 Overweight and obesity: An interactive insight. Australian Institute of Health and Welfare, November 2020}

^{4 Media release: Obesity closes gap on tobacco in health scorecard. Vic Health, 7 July 2022}

^{5 Overweight and obesity. Australian Institute of Health and Welfare, July 2022}

^{6 Inequalities in overweight and obesity and the social determinants of health. Australian Institute of Health and Welfare, June 2021}

^{7 Determinants of health: Diet. Australian Institute of Health and Welfare, July 2022}

^{8 Determinants of health: Insufficient physical activity. Australian Institute of Health and Welfare, July 2022}