Diet Tips - BODY MASS INDEX: A HELPFUL TOOL???

“I’m obese!” my husband proclaimed in a horrified voice. “This BMI thing, it says I’m obese!” pointing an accusing finger at the computer screen which displayed a picture of an oversized, bloated figure.

“Let me see that” I said, shoving him aside.

My extremely muscular and most definitely NOT obese husband was referring to the results of a Body Mass Index (BMI) calculation he’d done on www.nhlbisupport.com/bmi.

At 5’10, 210 lbs, the BMI calculator said my husband WAS obese based on height and scale weight, with no consideration of the fact that muscle weighs more than fat. Before he began to run blindly through the streets in an attempt to vanquish pounds of flesh, I sat him down and explained why BMI can be useful as a weight assessment tool, but that it is only provides part of the story.

What Is BMI?

BMI is an indication of whether you are overweight or a healthy weight as determined by a computation of your weight to height relationship.

How Do I Figure Out My BMI?

Calculating BMI takes only seconds and is free of charge when you go to a site like www.nhlbisupport.com/bmi. Simply input your weight and height and the calculator will deem you underweight, normal/healthy, overweight, or obese.

The Inherent Inaccuracy of BMI Calculations

Height-Weight tables such as the BMI consider a person’s frame size (height) in relation to weight, but NOT the percentage of muscle mass. The problem is that muscle weighs more than fat, so someone who is muscular can be considered “overweight” according to a BMI assessment while in actuality they do not have an abundance of body fat and are in fact at a healthy weight.

Other Options For Determining A Healthy Weight

Skin Fold Assessment: A measurement of the thickness of a pinch of skin and fat tissue from several places is taken and then entered into an equation. When done using a calibrated caliper this method can be quite accurate. However, inaccuracies arise if the person performing the test is not careful to do each of the “pinches” in precisely the same manner. Also, the accuracy decreases the more fat a person has.

Bioelectrical impedance, near-infrared light interactance, ultrasound assessment, arm x-ray assessment, computed tomography and magnetic resonance imaging. I’m not going to delve into these techniques because for most of us common folk, the expense of conducting them makes them an impractical tool.

The Gold Standard In Body Composition Assessment

Hydrostatic Weighing: While Hydrostatic Weighing is not cheap (about $50), it is considered by those in the health and fitness industry to be the best way to obtain an accurate body mass assessment.

Weighing is done by a quick dunk in a tank of water after the “testee” (now that’s a funny word) expels as much air as possible out of the lungs. The resulting weight is entered into an equation that computes body density and body fat. This method is considered extremely accurate because it assesses both body fat AND lean mass (muscle) percentages, so that scale weight does not dictate your results.

Take Advantage Of BMI

You might as well take advantage of BMI tests offered online – they won’t cost a penny, are non-invasive, simple, and quick. And BMI is a good tool to gather preliminary information about your body weight status.

But be aware that BMI, a weight/height assesment, does not tell the entire story about the state of your health. Talk to a health or fitness professional about other tests that can give you a more accurate picture. Otherwise, you may end up bumping into my husband, all in a lather, trying to outrun an ”obesity” problem that doesn’t exist.

Be Well!

Xoxo,
Health Sundae

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