The Body Mass Index is the standard measurement used by most professionals to measure whether you have a healthy body weight. It calculates your bodyweight by finding the ratio between your height and your weight.
This figure is then compared to the BMI chart. People with a BMI of between 20 and 25 are considered to have a healthy body weight. People below 20 are considered to have a lower than healthy bodyweight, while those over 25 are thought to be overweight. Those over 30 are considered to be obese and could be at risk of developing life-threatening health condition.
The scale isn't perfect. Those who have a higher than average amount of muscle mass, such as athletes and bodybuilders, will score higher on the scale, despite not being overweight. However, for most people, it is a suitable indictor as to whether they need to reduce their bodyweight.
The BMI is calculated by taking your weight, in kilograms, divided by their height squared. So, for example, if you were 1.6 metres tall, and weighed 65 kilograms, the calculation would be 65 divided by 2.56 (1.6 x 1.6). This would give you a BMI of 25.39, which would mean you were very slightly overweight.
You can easily calculate your BMI on the calculator below.
Source: Adapted from WHO (World Health Organization), 1995, WHO, 2000 and WHO 2004.
|Classification||BMI Category (kg/m2)||Risk of developing health problems|
|Normal Weight||18.5 - 24.9||Least|
|Overweight||25.0 - 29.9||Increased|
|Obese class I||30.0 - 34.9||High|
|Obese class II||35.0 - 39.9||Very high|
|Obese class III||>= 40.0||Extremely high|