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How To Calculate Body Mass Index Properly

Sep 23, 2009

Learn how to calculate your body mass index (BMI) to determine if you are at risk for weight-related health problems, as well as whether or not your weight is at a healthy level. This easy-to-use statistical calculation uses your weight and height to determine body fatness, and it was originally developed to help identify weight problems within a population. Though it does not determine body fat percentage, it is often used to get a general idea of whether or not you are a healthy weight.

How to Calculate Your BMI

Use the following equation to determine your BMI:

BMI = weight (pounds) x 703

            Height2 (inches2)

Once you determine your BMI number, find the related category below:

  • Underweight: 16.5 to 18.5
  • Normal Weight: 18.5 to 25
  • Overweight: 25 to 30
  • Obese: 30 to 40
  • Morbidly Obese: Over 40

What the Results Mean

If you are considered overweight by the BMI scale, it has been proven that you may have an increased risk for many weight related diseases and conditions such as hypertension, heart disease, diabetes, cancers, stroke, and sleep apnea.

If your BMI score indicates that you are obese or morbidly obese, your physician will evaluate your risk for these diseases using some other key indicators like waist circumference and family history.

Variables of BMI

While BMI is a good indicator of body fat, it does overlook some variables that make it not as accurate as some other forms of measurement. These include:

  • Women with the same BMI as men typically have more body fat.
  • Older people with the same BMI as younger people generally have more body fat.
  • Athletes with a lot of muscle mass can rank as obese, even though they have a low percentage of body fat.

Calculating your body mass index is a great way to easily determine if you are considered within a healthy weight range for your height. However, it should not be used to diagnose any disease or condition. If you are concerned about your results, talk with your doctor to determine if you are at risk for any of these weight-related diseases. If so, your doctor can work with you to create a plan that takes into account your diet, physical activity and family history to help lower your disease risk.

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