The BMI index was created in the early 1800s and is still used today to measure whether a person is in a healthy weight range. The BMI index is one of the few tools that is still used relatively unchanged 200 years after it was created. The BMI formula compares your height and weight to find out whether you are within a normal weight range or whether you are under or over weight. Although most people will know if they are putting on weight when they find their pants are getting too tight or they can see it when they look in the mirror, many doctors and also insurance companies rely on the results of BMI testing.
Insurance companies don't like to insure someone if they are high risk so they will often use a person's BMI to determine their risk. If a person is found to be overweight or obese by their BMI results then their health insurance costs can be significantly higher. Life insurance can also be higher for those who are overweight or if obese it can be refused altogether. An insurance company is protected it's own business and has the rights to refuse insurance to someone if they are high risk, however, unless other factors are taken into consideration, the BMI index is not always accurate.
To understand how the BMI is not always accurate let's take a look at how the BMI index is calculated. A person's weight is divided by their height squared – which is their height times itself. The BMI index is usually calculated using kilograms and meters, although the formula can be changed slightly to calculate using feet and pounds. For most of the population, the general BMI formula will give a fairly accurate result of what they weigh in relation to their height, but for some the result is not accurate because there are other factors involved.
What if we consider a weight lifter or a body builder, who's body is made up of a large percentage of muscle. Muscle weighs more than fat and takes up less room than fat. If someone who is solid muscle does the BMI formula then their result will indicate that they are overweight because their weight is too much for their height. However, it is because of their mass of muscle that their weight is what it is and not fat, so you can see how this result wouldn't be accurate. So if someone with a lot of muscle took the BMI test to apply for insurance, they could have higher premiums or even be refused insurance because they would be in the overweight range according to the BMI result, even though they don't have an ounce of fat on their body.
BMI results can also be inaccurate for children and also for very tall people, but generally for most average people the results will be accurate. If you calculate your BMI you can then work out what weight range you are in. A normal range BMI is between 18.5 and 24.9 so if you are within this range then you are in a healthy weight range. If you are below 18.5 then you are likely to be underweight, if you are between 25 and 29.9 then you are likely to be overweight and if you are 30 or higher then you are in the obese category.
The BMI index is a very good tool to use to check your weight range as long as you aren't in any of the categories that would make it inaccurate. When using BMI to determine your ideal weight, you will also want to use common sense and know how your body looks and how much fat you might have compared to muscle.