11 September, 2014    #15

Body Mass Index  & Waist Height Ratio
(BMI) & (WHR)

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Body Mass Index or BMI is the measure of relative body mass based on an individual's Weight and Height.


Devised in Belgium in the 1800s, BMI is defined as an individual's body weight or mass divided by the square of body height.  BMI is universally stated in metric units as kg/m2.


The Reference Ranges for BMI will vary depending on gender, ethnicity and body type. Below are generalized BMI Classifications and associated Reference Ranges.


BMI Classifications Reference Ranges
Under Weight  < 18.5
  ● Severe Thinness    < 16.0
  ● Moderate Thinness       16.0 - 17.0
  ● Mild Thinness       17.0 - 18.5
Healthy Weight    18.5 – 25.0
Over Weight      > 25.0
  ● Pre Obese      25.0 - 30.0
Obese  > 30.0
  ● Obese Stage 1      30.0 - 35.0
  ● Obese Stage 2      35.0 - 40.0
  ● Obese Stage 3   > 40.0

 WHO Classifications         ( < Less Than      > Greater Than )


A relatively new system, that I will call Waste Height Ratio or WHR, is thought to provide a better health-risk metric.  WHR states that your waist should not exceed ½ of your height.  For example, a 6 foot or 72 inch person’s waist should not be greater than 36 inches.  Or, a 183 cm person’s waist should not exceed 91.5 cm.



BMI has recently received criticism due to incorrect classifications associated with unusual body characteristics.  These individuals were either very short, extremely tall or highly muscular. 


For example, Arnold and Danny both have a BMI over 30, and are therefore considered obese and at a "higher risk" for cardiovascular disease.  Using the WHR system, Danny is still considered "high risk", while Arnold is considered at "normal risk" since his waist is less than half his height. 


However, for the vast majority of us, BMI is an excellent metric with a tiered classification system.


Individuals with a BMI greater than 25 are considered overweight and Life Style Changes may help (See Trax News Article #6 in the Library: “Life Style Changes”). If your BMI is 30 or greater, you are at increased risk for Cardiovascular Disease and Diabetes.



Currently, I am unaware of a tiered WHR system with incremental health risk, but thus far, WHR has received positive reviews.  Hopefully, continued research will eventually allow these systems to be combined.


Mike Kohut, President, DDMS





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