The Body Mass Index Alone Can’t Measure Fitness Or Health

The Body Mass Index (also called BMI) is a calculation that was developed almost 200 years ago. It was originally used as a way to describe the typical height to weight ratio of the average person. The formula is simple: your weight in kilograms divided by the square of your height in meters = your BMI. A typical online BMI calculator will accept data in pounds and inches and perform the conversion to the metric system behind the scenes. Hey, what can I say - Americans have a reputation for being lazy!

BMI Given “More Weight” Than It Deserves

Over time, the original purpose of this index was forgotten. It became a shorthand tool for estimating how much excess fat a person was carrying. This was linked (sometimes dubiously) to expected mortality by life insurance companies. Then, in 1998 the BMI standards for what is considered healthy were significantly lowered and made identical for men and women.

Now, a BMI over 25 is considered overweight. People with a BMI over 30 are labeled obese. This has resulted in a much narrower definition of “normal” and regular people are struggling to fit in. One problem is that we tend to assume that our ideal weight should always fall at the lower end of the normal range.

What This Means For You

Today, the body mass index is used by the medical community and pretty much the entire diet and weight loss industry to determine “healthy” parameters for body weight. Here’s a rundown of why this simplistic tool is problematic from a true fitness standpoint:

It doesn’t recognize variations in build and bone structure that can impact total weight

It doesn’t take differences between male and female physiology into account

It is not adjusted for ethnicity - it is based only on Caucasian norms

It can’t measure muscle to fat ratio - so, people who are very fit may have a high BMI

It doesn’t make allowances for “excess” weight in the elderly that may actually protect health

It is not suitable at all for measuring healthy weight in children

It makes no attempt to measure intra-abdominal fat (which is a better indicator of disease risk)

Getting A Grip On Health/Fitness Measurements

You can find BMI calculators online that let you select criteria like build and sex to come up with a slightly more accurate assessment. However, if you really want a clear-cut picture of your health and fitness level you need to look beyond this number. Getting your body composition measured is a good first step.

Also, take your family history into account. Is everyone in your family a little chubby but otherwise in good health and long lived? This means your normal weight may simply be outside the average range on the body mass index.

Bear in mind that cardiovascular fitness , muscle strength, endurance, and flexibility are good indicators of your overall health. So, take pride in every mile you walk, jog, or cycle, every pound you lift, and every inch you stretch. Those numbers are important too!

Body Mass Index to Fitnesstempo

Body Mass Index to Body Composition