Your body mass index, or BMI, is a health measure that uses your height and weight to work out if your weight is healthy, using those two factors.

The BMI calculation divides an adult’s weight in kilograms by their height in metres squared, so for example, a BMI of 25 means 25kg/m2.

BMI ranges
For most adults, an ideal BMI is in the 18.5 to 24.9 range.

For children and young people aged 2 to 18, the BMI calculation takes into account age and gender as well as height and weight.

 BMI Range:

below 18.5 – underweight range
between 18.5 and 24.9 – healthy weight range
between 25 and 29.9 – overweight range
between 30 and 39.9 – obese range

Accuracy of BMI?

BMI takes into account natural variations in body shape, giving a healthy weight range for a particular height.

Fat vs Muscle?

Muscle is much denser and heavier than fat, so muscular people, such as, weight trainers, athletes, and gym work out fans, may be a healthy weight even though their BMI is in a high band.

Your ethnic group can also be a factor as for example, adults of South Asian origin, may have a higher risk of some health problems, such as diabetes. These sort of variations might mean being outside the recommended weight band for your height still means your weight is classified as “healthy” for you circumstances. 

You should not use BMI as a measure if you’re pregnant. Get advice from your midwife or GP if you’re concerned about your weight.

Always consult your GP or Medical Practitioner about health issues.