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Body Mass Index


What is Body Mass Index (BMI)?

BMI is a number from the results of a calculation using a person’s weight and height.  The results of the BMI calculator are used as a tool to screen a person for potential weight problems due to body fat. Excess weight and body fat could put a person at risk for certain diseases such as high blood pressure, high cholesterol and type 2 diabetes just to name a few.

The Body Mass Index calculator results will fall into one of four weight status categories; underweight, normal, overweight and obese.  This status is used as an indicator of body fat.  Although the Body Mass Index calculator does not measure the percentage of body fat, research has shown that the BMI results have a direct correlation to body fat percent. 



How is BMI Used?

woman measuring waistBMI is used as a reliable screening tool to show potential weight problems, it is not a diagnostic tool.  The BMI calculator results will only show potential excess body fat and weight problems.  Additional tests and evaluations would also have to be performed to be certain. 

For example, a person may have a high BMI but due to their muscle mass, they may have a very low percentage of body fat.  Generally, however, if a person falls into the category of obese, they more than likely have excess fat and weight. 



What Additional Testing May Be Required?

Based on the results of the Body Mass Index calculation, your doctor may run additional tests such as a skin fold test to help measure the percentage of body fat.  Additionally, your doctor may evaluate your diet, family history and activity levels as well to measure your risk of weight related diseases.

The most accurate measure of body fat is the skin fold tests however there are many other methods of measuring fat.  If using the skin fold test you will want to have someone help you measure all the different skin folds recommended.

If you want just a quick and fairly close approximation of body fat, be sure to read this article on metabolic syndrome and scroll down to the body fat calculator.



How Is Body Mass Index Calculated?

BMI is calculated the same for adults and children.  The results for adults however are not gender specific whereas the results for children and teens is age and gender specific.  For all ages, you can use the BMI calculator on this site.

For children and teens, the calculation is the same as below, but the results are interpreted using the age and gender percentiles.  For more on children and teens body mass index, visit cdc.gov for their body mass index calculator.

Calculation

Measurement Formula
Pounds and inces weight (lb) / [height (in)]² x 703

Example: Weight = 175 lbs
             Height = 5' 6" (66 inches)

Calculation = 175 / (66)² x 703 = 28.24
Kilograms and Meters
(or centimeters)
Weight (kg) / height (m)² 

Note:  Since height is generally measured in centimeters, divide height in cm by 100 to get the measurement in meters

Example weight = 80 kg
            height = 168 cm (1.68 m)  

Calculation = 80 / (1.68)² = 28.34


The results of the above calculation would fall into the overweight status category.  Below shows the BMI and weight status based on the results of the calculator.

BMI Weight Status
Below 18.5 Underweight
18.5 - 24.9 Normal
25.0 - 29.9 Overweight
30.0 and above Obese




What Steps Should You Take

If you find yourself within the normal range of the BMI results but still feel you want to lose or tone, then focus first on exercising and eating healthier.  Don't try to cut calories to lose weight but instead focus on losing inches and toning muscles.

However if your results are in the overweight or obese category then first check with your doctor to see if additional tests should be run.  Also you will want to create a weight loss plan to lose weight and body fat.  Your plan should include eating healthy and exercising.  

Be sure to read these quick weight loss tips and exercise motivation tips to get your started on your weight loss program.




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Additional articles

Weight Loss Motivation
Unhappy with the results of your body mass index?  Then get motivated to lose weight with these tips.

 




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