The Body Mass Index (BMI) was invented by Belgian mathematician Adolphe Quetelet in the 19th century. It is calculated as the ratio of an individual's weight in kilograms to the square of their height in meters (kg/m2).
The formula is
where weight is measured in kilograms and height is measured in meters.
The BMI value obtained can be interpreted as follows:
- less than 15 - severely underweight
- 15-20 - underweight
- 20-25 - normal
- 25-30 - overweight
- 30-35 - obese class I
- 35-40 - obese Class II
- more than 40 - severely obese
While BMI is a widely used and easily accessible tool to assess an individual's weight status, it has several limitations and is not a perfect measure of body fat.
Firstly, it does not take into account differences in muscle mass, bone density, and distribution of fat, and thus may not accurately reflect an individual's overall health. For example, highly muscular individuals may have a high BMI but low body fat.
Secondly, it also does not take into account differences between adults and children, pregnant women, and older adults.
Moreover, the classification system for interpreting BMI results has limitations. For example, it does not distinguish between individuals who are overweight due to increased fat mass versus increased muscle mass.
Therefore, it is recommended to use BMI in conjunction with other assessments, such as body composition tests, to get a more comprehensive understanding of an individual's health status.