In last week’s post, we reported on the relationship of BMI, or body mass index, to mortality rates in COPD patients. Here’s how to figure out your own BMI:
- Weigh Yourself
Step on a scale and determine your weight.
- Convert Your Height to Inches Instead of “Feet and Inches”
Convert your height from “feet and inches” into just “inches.” For example, if you’re 5 feet 10 inches tall, your height in inches is (5 feet X 12 inches/foot) + 10 inches = 70 inches.
- Divide Your Weight by the Square of Your Height
Square your height in inches (inches X inches), and then divide your weight in pounds by that number. So, for example, if your height is 70 inches and your weight is 210, you would first compute the square of 70, or 70 X 70 = 4,900, and then divide 210 by 4,900. The calculated number in this example would be 0.043. This is not your BMI! There’s one more step in this calculation.
- Multiply by 703
Multiply the number you calculated in #3 above by a factor of 703. In our example, the BMI would be 0.043 X 703 = 30.13.
- The Quick Formula
BMI = (pounds / height2) X 703.
Why Is the Formula for BMI So Complicated?
You can thank the United States’ persistent use of the imperial system (feet and pounds) versus the metric system (meters and grams) for our complicated formula for BMI. If you used kilograms and meters instead of pounds and inches to determine BMI, the formula would be simpler: weight in kilograms divided by height in meters squared, or kilograms / meters2.
What If Your BMI Is in the Obese Category?
If your BMI is 30 or higher, technically you are considered obese. However, this is not a hard and fast rule. Since BMI doesn’t directly measure body fat, some people, like muscular athletes, may have a BMI of over 30 and yet not be obese.
While a higher BMI is associated with a lower mortality rate in COPD patients, obesity is not necessarily a good thing for you if you have COPD. If you’re obese, you have a higher risk of developing other health problems, such as Type 2 diabetes, high blood pressure, heart disease, stroke, and sleep apnea. Ask your doctor if your BMI is a problem.