8:13 p.m. - 2021-01-19
BODY MASS INDEX
One's body mass index (BMI) is calculated as kg/m2 (kilograms per meters squared). Therefore, BMI=weight in kilograms divided by height in meters squared. A healthy range for BMI is 18.5 to 24.9. Overweight is 25 to 29.9, and a BMI over 30 is considered obese. A BMI over 40 is called morbidly obese, in recognition of the many severe health problems that are associated with this much excess weight (diabetes, cardiovascular, some cancers, etc.) Some doctors substitute the terms Obesity Level One (BMI 30 to 34.9), Obesity Level Two (35 to 39.9) and Obesity Level Three (above 40).

There are plenty of online calculators for BMI, but a quick and dirty way to do the calculation in the English units with which we are all familiar is:
1. Multiply weight in pounds by 705
2. Divide above by height in inches
3. Divide a 2nd time by height in inches

Why does this work? Normally BMI is expressed in kg/m2. To convert kg to pounds, it is necessary to divide by 2.2. To calculate height in meters, the height in inches is divided by 39.37. So for the equation

BMI = kg/m2,

the numerator (kg) is expressed as pounds/2.2 while the denominator (m2) is (inches X inches)/(39.37 X 39.37). Rearranging the terms we get

BMI= (pounds/inches squared) x (39.37 X 39.37)/2.2
or
BMI= (pounds/inches squared) X (1550)/2.2
or
BMI=(pounds/inches squared) x 704.5

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