What is a Body Mass Index or BMI?

Answer:
Body Mass Index (BMI) refers to a measurement

developed in the 1800's and popularized in the 1980's when people were thought to be "losing control" of body weight and were becoming "obese" in the opinions of some experts. BMI measurements became commonplace for athletes, fitness buffs and medical professionals, and recommendations were plentiful regarding how to attain to and maintain a "healthy BMI".

Body Mass Index (BMI) is also known as the Quetelet Index, after the individual who invented the formulas, Adolphe Quetelet, a Belgian astronomer, mathematician, sociologist and statistician. Quetelet's formulas have changed only slightly since their introduction.

The basic formula to determine a person's BMI is Body Weight divided by the square of Body Height, and is typically expressed as kilograms per square meter, or in the non-metric world as pounds per square inch (of course the formula needs to be calculated in pounds and inches as well).

BMI results were really not intended to be used as hard and fast, emperically derived facts or figures. Rather, Quetelet's formulas are best used to approximate a person's affinity toward obesity by establishing benchmarks and measuring progress (or lack of it) during attempts to change lifestyle and/or eating habits.

It is said that a healthy BMI is somewhere between 18.5 and 25; and a BMI below 18.5 is considered underweight, while a BMI above 25 is considered overweight. Persons with a BMI below 17.5 are considered to be potentially anorexic, and persons with a BMI above 30 are considered obese. Persons with a BMI above 40 are considered morbidly obese.

Body Mass Index (BMI) has been used by the World Health Organization (WHO) for obesity around the globe. Because BMI can be quickly calculated through simple mathematical equations and does not require any special equipment or costly testing, it is frequently used as a broad categorization tool to qualify a person's physical status regarding the amount of weight they have in relation to their height.

But, that is about ALL the BMI really tells, since several other factors also play roles in overall physical condition, including a person's bone density, frame size, muscle mass, cartilage, water weight, and more. Indeed, some study data shows that some heart patients with BMI in the normal ranges were at higher risk of death from cardiovascular disease than people in the overweight range.

Because muscle is denser than fat, some athletes with highly developed muscles may find their BMI measure puts them into the obese category, simply because the formula for BMI measurement only takes into account weight and height, without regard for body-building muscle mass scenarios. Thus, measuring a percentage of body fat is a preferable measurement tool in such cases.