Body Mass Index (BMI)
BMI stands for Body Mass Index and is a measure of body fat for adults* based on height and weight. BMI is measured as [weight] / [height x height] and the unit for BMI is kg/m2.
Since BMI shows body weight adjusted for height, it can be used to compare and analyze the health effects for humans of different weights and heights. This makes BMI suitable as a common means of measuring overweight and obesity in humans.
For the average* adult, BMI falls into one of these categories.
Underweight
Less than 20.
Ideal
Non-Asian: greater than or equal to 20 but less than 25.
Asian: greater than or equal to 20 but less than 23.
Overweight
Non-Asian: greater than or equal to 25 but less than 30.
Asian: greater than or equal to 23 but less than 27.5.
Obese
Non-Asian: greater than or equal to 30.
Asian: greater than or equal to 27.5.
Notes
* Children's body fat levels change as they mature. As such, the measure of BMI for children (also referred to as BMI-for-age) is gender and age specific.
** BMI is merely a statistical measure and as such, it is possible to be healthy and yet have a BMI above 30.
Examples include:
- Bodybuilders who typically have BMIs above 30 due to high muscle mass percentages.
- The elderly who typically have very low muscle and bone mass.