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People who are overweight or obese have higher rates of death and illness than people of healthy weight. This is true, both on average and in relation to a range of specific conditions. These include cardiovascular disease, high blood pressure, Type 2 diabetes, sleep apnoea, osteoarthritis, psychological problems and reproductive problems for women.

Body mass index (BMI)

You can quickly check whether your weight is in a healthy range by calculating your Body Mass Index (BMI). It can be used for both men and women, aged 18 or older.

Your BMI is your body weight in kilograms, divided by the square of your height in meters.

For example, if you weight 75kg and you are 175cm tall (1.75m), your BMI = 75 / (1.75 x 1.75) = 24.5.

Rate your BMI

Your BMI will fall into one of four categories:

BMI (kg/m2) Classification
Less than 18.5 Underweight
18.5 to less than 25 Normal weight range
25 to less than 30 Overweight
30 or more Obese

Source: World Health Organization (WHO) 2000. Obesity: preventing and managing the global epidemic. Report of a WHO consultation. WHO technical report series 894. Geneva:WHO.

Limitations of BMI

BMI does not necessarily reflect body fat distribution or describe the same degree of fatness in different population groups.

Waist circumference

An alternative way to assess your risk of developing obesity-related chronic diseases is to measure your waist circumference. A higher waist measurement is associated with an increased risk of chronic disease. The risk levels presented below are for Caucasian men; and both Caucasian and Asian women.

Increased risk Substantially increased risk
Men 94 cm 102 cm
Women 80 cm 88 cm

Source: National Health and Medical Research Council (NHMRC) 2013. Clinical Practice Guidelines for the Management of Overweight and Obesity in Adults. Canberra: NHMRC.

For information on how to correctly measure your waist, visit the National Heart Foundation website.

Measuring overweight and obesity in children

As height and body composition are continually changing for children and adolescents, a separate classification of overweight and obesity for children is used based on age and sex.

Information is available on the Department of Health website, on the BMI cut-offs for children.