What is BMI anyway?


I’m sure many of you know about, or have at least heard of BMI. It stands for Body Mass Index, and is one of the many ways to determine if you are at a healthy weight, overweight, obese, or even underweight.

There are pros and cons to using BMI. The pro is that it is quick and easy, you can do it right now. The con is that it isn’t always accurate, since it doesn’t tell you about your body composition. Think of it this way, a really muscular football player probably weighs a ton compared to other men of his height. But, even though he may be the same weight as an overweight or obese man, he is certainly not. His BMI would tell him that he is overweight, but you can’t pinch an inch of fat on him. Similarly, you can be “healthy” or even “underweight”  on the BMI scale, but have a high percent body fat and no muscle.

Therefore, it is really important to take your BMI with a grain of salt. It is meant to just give you an idea of where you stand, but don’t forget that there are several exceptions. If you’re just your average Jane body type, BMI will likely be pretty accurately in line with your body composition. If you’re an athlete with a lot of lean body mass, your BMI may seem high.

Ladies and gents, get your calculators (iPhones) out….

◊ First, weigh yourself and measure your height.

◊ If you measured those in pounds and inches, use this formula:

  • [(weight in pounds) ÷ (height in inches x height in inches)] x 703
    • First multiply your height in inches by your height (ex. 72” x 72”)
    • Then, divide your weight in pounds by that value
    • Multiply the value you get by 703

◊ If you measured those in kilograms and meters, use this formula:

  • (weight in kilograms) ÷ (height in meters x height in meters)
    • First multiply your height in meters by your height (ex. 1.83 m x 1.83 m)
    • Then, divide your weight in kilograms by that value

If you’re really struggling with these calculations, you can always just use an online BMI calculator.

So what does that number mean?

BMI = less than 18.5 → underweight
BMI = 18.5-24.9 → healthy weight
BMI = 25-29.9 → overweight
BMI = 30 or higher → obese

Again, I cannot stress enough that BMI is not always accurate. It is just an idea to stimulate your thinking about where you stand. The best way to get an accurate depiction of your weight and health is to measure your percent body fat, or body composition, which I will be sure to explain shortly!

Don’t hesitate to ask me questions about calculating or interpreting your BMI! If you’re comfortable, you’re welcome to share yours!


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