The body mass index (BMI) also known as Quetelet index, is a statistical measurement which compares a person's weight and height. Though it does not measure the proportion fat present in the body, it is a handy tool to estimate an appropriate body weight based on the height of the person in question. Due to its simplicity and ease of measurement, it is the used extensively to identify obesity problems within population. However it is not considered appropriate to use as a concluding warning for diagnosing individuals. It was invented between 1830 and 1850 by the Belgian polymath Adolphe Quetelet that is why it is also known as Quetelet’s index.

Mathematically BMI is defined as the individual's body weight divided by the square of their height. Such that BMI= weight(kgs)/height2(m2).

This universally used formula in medicine produce a unit of measure of kg/m2 BMI of a person can also be determined using a BMI chart, which displays BMI as a function of weight on horizontal axis and height on vertical axis using contour lines for different values of BMI or colors for different BMI categories.

As a tool for measurement, BMI became popular during the early 1950s and 60s as obesity become prevelant issue in flourishing Western societies. BMI provided a simple numeric measure of a person's "fatness" or "thinness", enabling doctors to determinie overweight or underweight problems more precisely with their patients. It basically meant to be used as a simple medium for classifying lazy individuals with an average body composition. For such individuals, the present value settings are as follows: a BMI of 18.5 to 25 may suggest an optimal weight; a BMI lower than 18.5 hint the person is underweight while a number above 25 indicates that the unlucky person in question is overweight; however a BMI lower than 17.5 suggests that the person has anorexia or a smimilar disorder; a number higher than 30 suggests the person is obese and higher than 40 is a serious warning that is, the person is ghoulishly obese.

In the current scenario with obesity spreading like anything all over the world, BMI is widely used by millions of people especially to determine wheather they are obese or not. So that they can take relevant measures at the right time to prevent themselves from getting caught in the clutches of obesity. As it is always easy to fight with obesity when at its earliest stages rather than the stage when your degree of obesity is really high.