Calculating one’s Body Mass Index, or BMI, has become a popular way of categorising you into either underweight, normal, overweight or obese parameters. This method was devised by Adolphe Quetelet from Belgium as early as the mid 1800’s and the parameters are set as follows:

Below 18.5 – Under weight (A BMI of 17 qualifies for anorexia)
18.5 to 25 – Optimal weight
25 to 30 – Over weight
30 + – Obese

This statistical equation produces a number based on the weight and height proportions of the person. Notably, this calculation is used to calculate the body mass index of physically inactive people, not of people who are fit and exercise on a regular, meaningful basis. It is calculated by taking the weight of the individual and dividing it by the square of his or her height.

This method of discerning body mass started to become widely recognised by health professionals and fitness instructors in the 1950’s and 1960’s. It is important to note, though, that the purpose of the BMI was never to diagnose weight problems. Rather, it was only meant to provide a broad classification to give the doctor / professional and patient an idea of the body composition. It would not be accurately indicative, for example, in a tall person with a narrow frame. Similarly, if someone was to increase or decrease their normal weight rapidly, this would indicate that there was something wrong with the body, despite the fact that the BMI may reflect a healthy person based on their weight to height ratio. There are several theories regarding tweaking the equation slightly, but this remains the most commonly accepted method of calculation for now.

A high BMI indicates that the person is probably overweight, or even obese. This state can lead to many health risks, including diabetes, heart disease, high blood pressure and high cholesterol levels. In fact, there are even studies to prove that being overweight may cause or aggravate certain forms of cancer. A Body Mass Index that is too low means that the person is underweight and faces dangers such as osteoporosis, eating disorders and malnutrition. These result in lowered immunity against common illnesses, as well as more complex complications.

So the Body Mass Index has been most effective in providing doctors, dieticians, and even some ill-informed patients with a more accurate idea of where they stand in terms of how overweight or underweight they actually are. It is imperative that those using this specific method are aware that this is not a diagnostic tool or one that should define treatment, but rather one that can be used to support other medical data.