As overweight and obesity has become more and more epidemic, particularly in the United States, tools that assist in weight control have become more prevalent. A method used in weight control that has become particularly popular in recent times is the Body Mass Index, or BMI for short. The Body Mass Index is, to put it simply, a means for determining a person's ideal body weight.

Though the Body Mass Index has become widely familiar over the last decade or so, the notion of using an index to determine ideal body weight has been in existence for over one hundred years. A Belgian statistician in the 19th century came up with a formula that measured obesity. The statistician's name was Adolphe Quetelet and the formula he devised to measure obesity was, appropriately enough, called the Quetelet Index of Obesity. The Body Mass Index is, for all intents and purposes, an updated description of the Quetelet Index of Obesity.

The Body Mass Index, or the Quetelet Index of Obesity, uses a mathematical formula to determine a healthy weight. The Body Mass Index is not just a diagnostic for overweight, however, but offers a diagnosis for underweight as well. The formula used by the Body Mass Index to determine a person's weight health is body weight divided by height squared.

In the 1980's, the BMI achieved popularity in the medical field. Prior to this, objective considerations of body weight were based solely on how tall a person was. The problem with this sort of measurement was that it was too narrow in its consideration of a person's body composition, and didn't offer enough information about a person's physical make up and where he or she stood in relation to ideal body weight.

The Body Mass Index gave a thorough consideration of body make up by providing weight ranges, from healthy to unhealthy, and the BMI came to be the standard measure for obesity during the 80's. In the 1990's, as issues of overweight became more significant, US government efforts to encourage better health resulted in Body Mass Index discussion on a much wider scale, and beyond the medical profession.

Calculators that determine BMI are today frequently found on the Net. Virtually anyone can now plug in their height and weight measurements and get a BMI weight composition reading. The BMI was developed as a means for classifying extreme body weights, particularly obesity, so using BMI as a standard measurement for optimal body weight health is inherently problematic. In other words, BMI was essentially developed to categorize the bodies of obese people, and expanding its use beyond this original intent and expecting perfect results is not particularly realistic.