The Body Mass Index, also known under the BMI acronym, is one of the most commonly used tools to determine whether a person is overweight or underweight. It is a formula used by many nutritionists to help people reach the perfect weight and consequently a good health. Even though modern medicine still applies the principles of the BMI, this formula was developed somewhere between 1830 and 1850. Its creator was Adolphe Quetelet who was a Belgian polymath. He came up with the formula while developing social physics.
Adolphe Quetelet was a well known sociologist, astronomer, mathematician and statistician of the 19th century. He strongly believed that statistics and probabilities influence human lives too much, so they have to be taken into account. Since he was the creator of the BMI, this formula took his name for a while and was called the Quatelet Index. This index managed to bring light into the medical industry, which was not very advanced back then. Because of the advantages of this formula brought, it soon began to be the most commonly used tool to determine the right weight someone should have.
How to calculate the BMI
The BMI is very easy to calculate. All one needs is to place the height and the weight of a person into a simple equation:
BMI = mass(kg)/(height(m))2
This means that the BMI is the weight divided by the height in meters squared. Since this formula is used all over the world it has been adapted to other systems of measurement. For example, the BMI can be calculated by dividing the weight in pounds by the height in inches squared. The result has to be multiplied by 703. So, the equation looks like this:
BMI = mass(lb)x703/(height(in))2
If the weight is measured in pounds and the height in feet squared, the result has to be multiplied by 4.88. When the weight is measured in stones and the height in inches squared, the result should be multiplied by 9840. This way, the formula is adapted to fit all cultures.
Even though many people know that Quetelet was its creator, the truth is that the term body mass index became popular only in 1972, when Ancel Keys published a paper on it in the July edition of the Journal of Chronic Diseases. Keys considered that this was the best tool to establish the body fat percentage in the human body.
What are the advantages of the Body Mass Index?
- At first sight, one can see just how easy it is to calculate. This makes it accessible for everybody. This tool can be used even by simple people who do not have to see a doctor to divide their weight by the height squared. This way, people can learn by themselves if they are overweight or if their weight is below normal. All they need is the chart where they can see in which category they fit.
- It is a useful primary tool in diagnosing obesity. Because of that, this formula is used by almost all physicians, nutritionists or trainers in health centers.
- It is cheap. There are many devices nowadays that can calculate the percentage of fat in the human body. They use innovative technology that allows one to see just how large the fat deposits are and how much weight one needs to lose or gain. Unfortunately, all these tools are very expensive, which is why not everybody can afford them. There is no expense to be made in order to calculate the BMI, which makes it very popular.
What are the applications of the Body Mass Index?
- The BMI is used first of all by doctors to help their patients deal with their weight problems. This tool can be used both in the case of overweight and underweight people.
- Secondly, it is used as a statistical device. Even though some say it has its flaws when it comes to diagnosing individuals’ weight problems, this formula is excellent to identify trends. For example, statisticians use it to indicate the general trend of the population in what concerns the weight. With its help, researchers found out that there is a trend nowadays towards children obesity and that measures have to be taken to prevent it from expanding. Moreover, countries can find out the general state of health of its population. This way, the US has decided to take measures to lower the alarming number of overweight and obese people who account for the 63% of the American population.
- Thirdly, it is used for medical underwriting processes. A very good example is that of insurance companies, which have very rigorous criteria when it comes to health insurance. The health insurance rates and premiums are decided taking into account several risk factors. Obesity is one of them, which can determine the insurance company to raise insurance rates for obese people or even deny it in some cases. However, the limits are set by each individual insurance company. Still, most of them deny the application of the morbidly obese individuals, no matter how much they are willing to pay.
What are the main categories of classification?
Even though in some countries numbers can differ, the main categories generally adopted group people into seven classes as following:
- Severely underweight: the BMI is less than 16.0.
- Underweight: the BMI ranges between 16.0 and 18.5.
- Normal: the BMI ranges between 18.5 and 25.
- Overweight: the BMI ranges between 25 and 30.
- Obese Class I: the BMI ranges between 30 and 35.
- Obese Class II: the BMI ranges between 35 and 40.
- Obese Cass III: the BMI is over 40.
To make people aware of what normal is, the researchers estimated that a person that is 1.8 meters tall should have between 59.9 and 81.0 kilograms. In pounds, it means between 132 and 179lb. Even though these groups are not always very accurate classifications, they are generally correct with some exceptions. Because of that, people who have weight problems or who believe their weight is not within the normal range, should go to the doctor to check whether they have to adopt a special diet or not.
The weight issue is a very popular one nowadays and people do whatever they can to look as skinny as possible. Because of that, the BMI is probably used now more than ever. In spite of the general preoccupation to lose weight, the population is confronted with what some might call an obesity epidemic. Ignorance in establishing the right weight is not one of the causes of this epidemic. Some say that it is exactly this constant preoccupation with being slim that has caused people to gain weight. Things make sense if one were to count how many fad diets are available nowadays that promise people to lose weight in a very short period of time, ignoring the consequences of their actions.
The fast food industry is also one of the major causes of the constantly growing number of obese people nowadays. All the preservatives and additives in the fast food have a very negative impact on the health and on the weight of a person. Moreover, most fast food products contain more fats than they should and have ingredients that create addiction. Scientists have studied this problem and reached the conclusion that people no longer have only four tastes: sweet, salty, bitter and sour. Now people have the fifth sense called “umami”, which is responsible for the taste of fatty foods. This can explain the fact that some simply cannot help themselves when it comes to certain types of foods.
Another problem of the modern world that leads to obesity issues is the sedentary lifestyle. Even though people know their BMI shows they are overweight or obese, they do not make changes that could help them lose the extra pounds the healthy way. People no longer do simple things like walking or climbing stairs. They prefer traveling even very small distances by car or taking the elevator instead of climbing one or two floors.
With all these problems of the modern life, physicians go back to the traditional tools of establishing the percentage of fat in the human body. One of them is the Body Mass Index, which is seen as a reliable tool in spite of its flaws. There have been many other tools to help people decide which their perfect body weight is, but all these have had so many disadvantages, that using them is not an option for everybody. Since the BMI is so accessible, there are many physicians who still use it to establish whether their patients are overweight or underweight.
However, a simple formula cannot replace what the human eye can see. So, the experience of a doctor can fill in the gaps left by the BMI formula and reveal whether someone is having weight problems or not.
As an overall conclusion, it is a wise choice to use the Body Mass Index as long as there are also other factors that are taken into account when choosing the proper diet.