|Calculating BMI is one of the best methods for population assessment of overweight and underweight. Because calculation requires only height and weight, it is cheap and easy to use for clinicians and for the public. The use of BMI allows people to compare their own weight status to that of the general population. Body Mass Index (BMI) is a simple index of weight-for-height that is commonly used to classify obesity, overweight and underweight in adults. Body Mass Index is defined as the weight in kilograms divided by the square of the height in meters (kg/m2). For example, an adult who weighs 74kg and whose height is 1.8m will have a BMI of 22.8. A BMI of less than 18 suggests you are under weight. A BMI less than 18.5 indicates you are thin for your height. A BMI between 18.6 and 24.9 indicates you are at a healthy weight. A BMI between 25 and 29.9 means you are overweight for your height. A BMI of 30 or greater indicates obesity. BMI provides a simple numeric measure of a person's thickness or thinness, which allows health professionals to discuss overweight and underweight problems more objectively with their patients. However, Body Mass Index has become controversial because some people, including physicians, have come to rely on its apparent numerical authority for medical diagnosis, but it was never the BMI's purpose; it is meant to be used as a simple way of classifying sedentary (physically inactive) persons, or rather, populations, with an average body composition.