The term Body Mass Index more popularly referred to as BMI is on many people’s lips, although very few are actually aware of its meaning or significance.

As its name implies, the Body Mass Index is essentially an Index, used for evaluating the optimal weight of a person in proportion to his/her height. It is also known as the Quetelet Index named after its Inventor, Lambert Adolphe Jacques Quetelet. This came into recognition primarily with statistics and probability theory and has since branched into various models of social Normal distributions.

It is used mostly as an indicator for medical purposes rather than the beginning and end of what a person’s weight ought to be for a given height. It has been found to be quite useful in the study of obesity and for early detection of telltale signs of impending obesity in the future. It has its own shortcomings and limitations in that the BMI takes into account only the height for determination of the optimal corresponding weight for that height completely ignoring other important factors such as the body frame size, extremely muscular bodies such as those of athletes, as against those with flabby fat bodies on the other end of the scale, bone mass density of children and the very old as against normal youthful and middle age persons, those with amputated limbs, pregnant women; all of which can significantly affect the interpretations derived from a BMI figure given in isolation without any reference to the above stated extenuating factors.

Due to these anomalies, there are numerous irregularities that occur in the calculation of health insurance premiums demanded by some American health insurance providers classifying some normal and healthy people as “obese” going by a BMI rating alone.

Body Mass Index is calculated by dividing the weight in kilograms by the square of the height in meters.  According to World Health Organization, a Body Mass Index of 19-24 is described as normal.

Nevertheless, the age of a person has also to be taken into account in arriving at a realistic BMI. Therefore certain adjustments have to be made in respect of old persons as well as for children below 18 years of age if you are to arrive at a proper assessment for the BMI rating to be a meaningful indicator. A BMI value taken without the age in respect old persons and children under 18 would lead to incorrect interpretations and conclusions. BMI obtained for older persons would yield a higher value than the actual position whereas the reverse of it is applicable to children below the age of 18 years. For the calculation of Body Mass Index for persons with amputated limbs, there is a separate table on the average weight of arms, legs, etc. to be considered for effecting necessary adjustments to the BMI otherwise obtained by dividing body weight in kg by the square of the height in meters. This value must be the actual body weight to be added.

Doctors differ in the interpretation of this mass number as applicable between men and women. Men are generally composed of a greater proportion of muscle mass, which shifts the BMI at one point up or down. Nevertheless, even this approach is often criticized as the Body Mass Index; since in general, the relationship between weight and body fat and muscle mass can be ignored. People with above average muscle mass often reach a BMI indicative of being overweight compared to height.

So far, experts and scientists are not fully agreed on the value of calculating a body mass index. Furthermore, no correlation can be found between a slight increase in body mass index and increased mortality or increased risk of illness, without incorporating considerable adjustments in respect of extenuating factors. The same also applies to the various other standard formulas or rules for determining the body weight.