Thursday, December 13, 2007


Chris and I were talking tonight, and she mentioned how she just calculated her BMI — and I was appalled. Not because she calculated her BMI, but because I am a personal trainer and have yet to discuss BMI on this blog.

So, for all you people out there wanting your BMI (body mass index) calculated, here is what you need to know. First, you need to know what body mass index is. Then you need to know the formula.

Body mass index, commonly referred to as BMI, is a relationship between height and weight that helps determine overall body fat as a health risk factor.

The formula is simple:
your weight in kilograms (2.2 kg per pound)
divided by your height in meters (.3 m per foot), squared

For a 100 pound person who is 5 feet tall, her BMI formula would be:
45.45 kg
divided by 1.52 m, squared

45.45 divided by 2.31
equals 19.6

Chris votes for letting the National Institutes of Health BMI calculator do the math. However, she concedes that the formula above works, no matter how hard she tries to mess it up.

By the way, this formula will not work on bodybuilders -- their muscle mass is so dense, the formula will show them as overweight every time. However, for the rest of the population, it should work.

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