Is the Body Mass Index (BMI) a good measure of overall fitness?

Your weight to height ratio is an excellent measure of overall fitness. Learn how to calculate this ratio using the Body Mass Index (BMI) method.

By Ensure Fitness staff

There are many methods of calculating your overall fitness level but there is one that doesn’t require any special tool or device to get an accurate measure. The Body Mass Index (BMI) takes into account two ingredients: height and weight. The BMI can serve as an important measure of fitness at the beginning of a weight loss program and can also be used to gauge your overall fitness over time.

What is the Body Mass Index (BMI)?

Put simply, the BMI is a measure of your weight in relation to your height. Taller people naturally weigh more so a measure of weight only doesn’t provide an accurate measure of fitness by itself. By taking in account both height and weight, the BMI is a better measure of overall fitness than weight alone.

The BMI is essentially a measure of your “fatness” or your weight in relation to your height. It is used as an overall and general measure of fitness by focusing on the amount of fat you have on your body. The BMI is used to place you into one of four categories. These categories include underweight (less than 18), normal weight (between 18 and 25), overweight (25 to 30), and obese (over 30).

The great thing about the Body Mass Index is that it works equally well for men and women. There is no need to use different numbers to place you in a category of overall fitness. These categories are used to indicate the potential for other risk factors such as high blood pressure, diabetes, and high cholesterol.

How to calculate your BMI

Calculating your BMI is quite simple. Just take your weight in pounds and divide by the square of your height in inches. Then multiply the resulting number by 703. Or, you can calculate it this way:

((weight * (height * height)) * 703

So a person who is 65 inches tall (5 feet 5 inches) and weighs 155 pounds has a BMI of:

((155 * (65 * 65)) * 703 = 25.8

This would place this person in the overweight category according to the Body Mass Index. If you are having trouble calculating your BMI, try using the Body Mass Index calculator at the Mayo Clinic’s website. It is one of the best and easiest to use on the web.

Keep in mind, though, that the BMI can miscalculate the fat in your body in relation to your height for several reasons. The most important reason is your current fitness level. If you are unusually muscular, your BMI will likely place you in a category higher than where you belong. Similarly, if you lack a regular amount of muscle mass, the BMI can underestimate you body fat. Remember to take these factors into account and not place too much emphasis on your BMI number and category.

How to use the BMI as a part of a fitness program

The BMI is a great measure of overall fitness that goes beyond just a onetime measure. You can use the BMI to gauge your fitness progress by calculating your body fatness at regular intervals. In conjunction with your weight, the BMI can give you an objective measure of your overall health by placing you within one of four categories so you can gauge how close you are to your fitness goal. Certainly, you should be working toward the “normal” BMI category.

Start by measuring your BMI and continue to measure it at regular intervals. Given that your height will not change significantly over time, any change in your BMI must be due to a gain or loss of fat. Your BMI will not change drastically over short periods of time so monthly or even quarterly (every 3 months) may be an appropriate interval depending on your current fitness level and your goal of either becoming more fit or maintaining your current fitness level. Either way, the BMI can be a useful tool that tells you more about your overall fitness level than just a measure of weight can tell you.