School of Weight Loss

(Originally published January 12, 2009)

Body Mass Index (BMI) is a measure of the relationship between your weight and your height.  The theory behind it is that if your weight is high relative to your height, that indicates a health risk.  However, it is largely regarded now in the fitness community that calculating BMI is mostly a waste of time.

The only usefulness of BMI is in extreme cases.  BMI is useful for identifying an obese individual who needs to lose weight immediately to avoid serious health risks.  In this instance, BMI can be used to show the severity of the person’s problem and indicate how much weight loss is needed to get down to a healthy level.

Other than that, for your average individual, I would throw BMI completely out the window.  As an example of its uselessness, when I was in my peak physical condition a little less than a year ago, I was 5′9″ and 183 pounds.  This results in a BMI of 27, which is right in the middle of the overweight category.  I believe I can even go up to 190 pounds by adding more muscle mass without increasing body fat and still look and feel in great shape.  This would raise my BMI to 28, while 30 is considered obese.

Just for kicks, I went and calculated the BMI of the top three running backs in the National Football League this season.  The results: Adrian Peterson 28.6 (overweight), Michael Turner 35 (obese), and DeAngelo Williams 32 (obese).  So, apparently two of the top three running backs in the NFL are obese, while the other is overweight.  See a problem with this?  These guys are some of the best athletes in all of sports.  In fact, I’d be willing to bet that there are a few world-class sprinters who are “obese”.

The reason for this absurdity is that BMI does not take body fat % into account.  The people I mention above have a very high amount of lean muscle mass with relatively little fat mass.  This gives them a high BMI, while they are actually in excellent physical condition.

So, do not waste too much time worrying about your BMI unless you are in poor shape and fall into the obese category.  Even so, just worry about dropping body fat in a healthy manner while preserving muscle mass.  Your BMI may not drop as quickly as your fat does, but you will be much happier and healthier.

Just for the sake of completeness, the formula for calculating BMI is as follows:

weigh in kg / height in m^2

or

weight in lbs * 703 / height in inches^2

Now that you know it, remember that it is useless.  Focus on using sound nutrition and exercise principles to lose body fat and get yourself healthy.  The numbers aren’t the important thing.

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