What is Body Mass Index (BMI) and how to calculate it?

Wednesday, July 15, 2009

The Body Mass Index is a calculation of your bodyweight and height and will determine if you are obese, overweight, average, or underweight. The problem with the BMI is that it is not too accurate in the sense that it does not take into consideration ones muscle mass. Some people weight more because they are carrying more muscle on their frame than others, such as body builders, and according to the BMI they would be considered obese yet their body fat may be as low as 6 percent.

The BMI is basically just a guideline and if you want more accuracy then I would suggest you use a skin caliper. The skin caliper is much more accurate in determining how much body fat one actually has by taking measurements at different sites of the body and then calculating the measurements together to come up with the total body fat percentage. These calipers are readily available at most gyms or if you train with me I would do the measurements for you and keep them logged down and checked monthly.

Here is the formula for how to calculate the BMI:

BMI = Weight in Pounds / (Height in Inches) x (Height in Inches) X 703

So basically you are going to multiply your height in inches by itself then take that number and divide it by your height in inches and multiply that number by 703.

Or if you want to calculate it in metric system then you would calculate it by the following formula:

BMI = Weight in Kilograms / (Height in Meters) x (Height in Meters)

Once you have determined your number then match it to this chart to determine your health range:

o A BMI of less than 18 means you are under weight.

o A BMI of less than 18.5 indicates you are thin for your height.

o A BMI between 18.6 and 24.9 indicates you are at a healthy weight.

o A BMI between 25 and 29.9 suggests you are overweight for your height.

o A BMI of 30 or greater indicates obesity. If you are obese, try consulting a doctor or losing weight.