Thursday, October 11, 2012

What is BMI and how to calculate yours

BMI stands for Body Mass Index and is a calculation that many people use to determine whether a person is of normal weight or not. It is considered a good indicator of health and uses a person's weight, height to calculate the BMI number. It's a preferable method to other more accurate methods due to the fact that it's inexpensive and on invasive. Doctors use BMI as the first indicator of whether or not to do more tests.

There are some cases where BMI is not a good indicator of overall health. For instance, a body builder might have a high BMI but not actually be overweight or fat, instead they just have a higher muscle mass than others. In this case, further tests may need to be done to determine actual health. But, for the most part, BMI is a good measurement to use to determine where you stand health wise.

It's easy to determine your BMI. Just a little easy math. I promise.

Here is the formula:

(Weight lbs / Height inches²) 703

That is: Weight in lbs, divided by height in inches squared, times 703.

An example for a 140 lb 5 foot 5 inch person:

(140/4225) = 0.03313609467455621301775147928994 x 703 = 23.3 (round up)

On the chart this person would be considered to be within a normal weight range. It is important not to round up until you get the final BMI answer.

The chart looks like this:


Health Status

Below 18.5


18.5 - 24.9



Over weight

30.0 and Above


For adults, the chart is not age or sex specific, but for kids, and teenagers, then there are other charts to use and another formula that takes into consideration age and sex. This points out a problem with the use of BMI, regarding the sex of the individual because men naturally have more muscle than women, and women more fat than men. But, it is a good start when trying to determine whether your own weight is within a healthy range or not.

You can also local BMI calculators online.

A good one is put out by the National Heart Lung and Blood Institute and is here: BMI Calculator

The most important idea behind figuring your BMI is to get a good start on knowing if you're at a healthy weight range, or not. If not, then it is time to do more research into your personal situation to determine if you're really at an unhealthy weight, whether under weight or overweight. There are many risks associated with both that need to be addressed. Using the same person above but moving their weight to only 180 lbs only 40 lbs over classifies someone as obese with a BMI of 30.0, which can cause many health problems such as diabetes, heart disease, high blood pressure and more.

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