Why BMI Is Flawed

If strength training is a regular part of your fitness routine and you’ve managed to pack on some serious muscle, you might find yourself in the “overweight” category according to your Body Mass Index (BMI) score.

In our clinic, we assess many athletes and bodybuilders with less than 15% body fat, yet their BMI scores are above 25, placing them in the “overweight” or in some cases the “obese” category. To give you some context, a male athlete with 15% body fat will have decent muscle definition with a hint of ab definition. This is clearly not an obese person, so why does their BMI score classify them as such?


How Do I Calculate My BMI?

Determining BMI doesn’t require any special equipment, making it a favourite metric for physicians and health researchers. BMI is calculated using your height and weight as follows:

calculate bmi

You can see which category of fatness you fall into based on your BMI:

bmi chart

The Sub-15% Body Fat / Overweight Paradox:

The major flaw with BMI is that it doesn’t account for individual differences in body composition. While fat, muscle, and bone mass vary from person to person, the BMI range was developed using aggregate population data. People with a high degree of muscle are outliers that don’t fit the BMI model. Conversely, you can have an optimal BMI but very low muscle mass, which isn’t ideal from an overall wellness perspective.


Body Composition – A Better Approach:

Though more accurate methods are available to assess fatness, BMI continues to be used at both the individual level and in population studies. In population studies, data-averaging effects make BMI a reasonable metric to track fatness. At the individual level, there are better methods for monitoring fatness.

At Body Insight, we use two complementary technologies to get a true picture of your body composition: Body Composition Analysis and 3D Body Scanning. This dual approach allows us to determine your fat mass and muscle mass. In turn, we can get a much more accurate assessment of your overall health and health risks based on your body composition. The best part? By measuring your fat and muscle mass, we are able to track changes over time to ensure any fluctuations in your body weight are coming from fat loss or muscle gains.

We’d love to host you at our clinic. Call (647) 347-9572 or email us at info@bodyinsight.ca to book an appointment or to learn more about our testing services.