What is BMI (Body Mass Index)?

The body mass index (BMI), or Quetelet index, is a statistical measurement which compares a person's weight and height and indicates the fat percentage in one's body.

As it is easy to calculate, it's usually used to determine whether individuals are normal weight, underweight, overweight or obese.

Body mass index is defined as the individual's body weight divided by the square of his or her height. Unit: kg/m^2

Formula:


Here is a list of BMI and what they indicate:

BMI range – kg/m2    Category
less than 16. 5               Severely underweight
from 16.5 to 18.4           Underweight
from 18.5 to 24.9      Normal
from 25 to 30                Overweight
from 30.1 to 34.9           Obese Class I
from 35 to 40                Obese Class II
over 40                      Obese Class III

So, if your BMI doesn't come in the range of 18.5 to 24.9, then you must take action to keep yourself fit.