Calculate Your Obesity Risk - BMI Measurements

Body mass index, otherwise known as "BMI" is a measurement doctors, trainers and other health professionals often use to calculate your risk of developing obesity. Using a BMI chart, you can decide whether your weight is below, at or above average for an average person of the same height.

BMI measurements became popular during the 1800s, when a gentleman by the name of Adolphe Quetelet devised a tool for calculating one's weight status, which translates into ones overall health.

How BMI Works
While there are many BMI calculators you can use online to find out what your BMI is, you do not have to necessarily rely on them to find out what your BMI is. In fact, to calculate body mass index a person or their healthcare provider will often use specific mathematical formulas.

BMI = weight in kg/height (m) (squared)

Let's say for example you are 125 pounds and 5 feet 6 inches tall. First, you will need to convert your weight into kilograms. You do this by dividing your weight by 2.2. Next you will convert your height to meters.

You can do this quickly and easily by using free tools available from the National Heart Lung and Blood Institute: http://www.nblbisupport.com/bmi

125/2.2 = 56.82kg

56.82/2.82 = 20.1 BMI

Now, let's take this formula and convert using pounds and inches, the more common measurement in the U.S. In this case the BMI formula goes something like this:

BMI = 703 X weight in lb/height (in) (squared)

703 X 125/66(2) = 20.1 BMI

What Does This All Mean?
Now that you know how to calculate your BMI, what is the point? You can use the BMI measurement to assess how healthy your current weight is. While BMI is a useful tool, do note it is more effective when utilized in conjunction with other measurements, including waist measurements.

Many people feel using BMI alone is not a good predictor of health, because BMI accuracy does not always account for individuals with larger waists that are lean and muscular or athletes for example. A woman that is 145 pounds and 5 feet 3 inches tall would have a BMI over 25, suggesting she is overweight.

However, if more of her weight comes from muscle mass than fat, BMI may not be the best overall predictor of health.

The goal of BMI measurements is to provide individuals with a relative idea of how fit they may or may not be. If you find your weight over the limit for "normal" individuals, formal additional testing may be needed to confirm your health status. A fat caliper test for example, can help healthcare providers provide a better review of how fit you are instead of how much you weigh.

If you do use BMI, you should familiarize yourself with the "norms" as provided by the U.S. Department of Health and multiple other agencies including the NHLB. These organizations provide charts that help you assess what "category" you fall in. These may differ depending on the instrument you use, but typically you can discover the relevance of your overall BMI by noting the following:

• If your BMI is less than 18.5 then you may be underweight.
• If your BMI is less than 25 and above 18.5 then you fall into the "normal" category.
• A BMI less than 29.9 but more than 25 suggests you may be overweight.
• A BMI over 30 suggests you are obese.

If you fall into the latter two categories, and even if you find you are underweight, you should seek guidance from a qualified healthcare professional as soon as you are able.