Body Mass Index

The Body Mass Index (or BMI) is a tool used by health professionals to help determine whether a person is a healthy weight. BMI is calculated by taking a person’s weight and height measurements and using them in the following equation:
 
BMI= weight/(height)2 and is expressed in kg/m2 
 
What do the BMI ‘numbers’ mean?
 
Your BMI provides a guide to your risk of having health complications.
 
The following BMI groupings are generally accepted:

• <18.5 kg/m 2 - underweight
• 18.5 - 24.9 kg/m 2 - healthy weight
• 25.0 - 29.9 kg/m 2 - overweight
• >30.0 kg/m 2 - obese

A BMI in the healthy weight range carries the lowest risk of disease.
 
Do the BMI categories apply to everyone?
 
BMI should only be used as a guide to your health. There are certain groups of the population where BMI is not a good indicator of health. These include:
·         Muscular people (such as athletes)
·         Some ethnic groups
·         Infants, children and adolescents
One reason for this is that BMI does not distinguish between body fat and muscle mass. If you have a higher muscle mass, you may have a higher BMI but this may not mean you are at a greater risk of disease. In determining your risk, it’s useful to consider other measures (such as your waist to hip ratio, and your body shape) along with your BMI.
Interpreting your BMI should always be left to a professional, such as an Accredited Practising Dietitian.

If you are concerned about your BMI an Accredited Practising Dietitian can provide expert, tailored dietary advice to help you achieve or maintain a healthy weight.