BMI: What It Measures, What It Doesn’t, and How To Fill In The Gaps

Increasingly, fitness-focused folks have begun questioning whether their Body Mass Indicator (BMI) is actually a good indicator for weight loss. It’s the gold standard amongst physicians, many of whom argue that it’s a quick and simple way to determine a patient’s weight category and consequent risk of developing health problems, such as diabetes and heart disease. But, is it really the best indicator to use for weight loss? How about for overall health? Let’s explore what BMI can tell us, what it can’t, and what other indicators we can use to accurately measure our progress as we work toward total health optimization. 

How can I easily calculate my own BMI? 

Plug your values into this formula: BMI=(Weight in Pounds x 703) / (Height in Inches x Height in Inches) 

Great! Now that I know my BMI, what does it tell me? 

Your BMI will indicate which weight category you fall into: 

Underweight: BMI below 18.5 Normal: BMI between 18.5 and 24.9 Overweight: BMI between 25 and 29.9 Obese: BMI of 30 or higher 

This designation, however, is only indicative of one health marker--obesity. 

If that’s the case, then what does my BMI not tell me? 

Your BMI, in general, is an inaccurate measure of total health or efficient weight loss. For example, it doesn’t take into account the ratio of fat versus lean muscle in the human body. In some instances, an athlete who regularly exercises can erroneously register as overweight on a traditional BMI test. Your BMI also doesn’t indicate the unique fat distribution on your body. This is important because not all fat is equally harmful. The more fat you have specifically around your middle—visceral fat—the higher your risk is of diabetes, heart disease, and even death. Obesity, as a disorder, is complex, and no single measurement can represent a healthy weight for all. 

So, what are the best indicators for measuring weight loss if not my BMI? 

Waist-to-Height Ratio: Whereas BMI compares weight to height squared, this measurement compares waist circumference to height, which is important since it takes into consideration visceral fat. 

Body Measurements: Good old-fashioned measuring tape can be your best friend if you choose to track your weight loss by measuring various body parts, such as your arms, waist, and legs. This method is especially useful for indicating localized change. For example, if your weight isn’t budging but your waist measurement is shrinking weekly, you’re actually building lean muscle mass and shedding fat at the same time! 

Resting Heart Rate (RHR): A properly functioning cardiovascular system is essential for every badly function, including those crucial for weight loss. A pro tip for using this particular weight loss indicator is to try to find your resting heart rate first thing in the morning before you get out of bed. 

Body Mass Composition (BMC): One of the major drawbacks to using your BMI to measure weight loss is that it doesn’t differentiate fat from lean muscle tissue in the human body. A BMC test will calculate your body fat percentage in a way that’s similar to the Waist-to-Height Ratio method but with a few additional measurements, including the wrists, hips, and forearms for women. 

Armed with the knowledge that your BMI is only one simple test to measure obesity levels and not an accurate indicator of overall total body health, you can start incorporating some of the other helpful tools above. However you decide to measure your weight loss, our best advice is to set realistic, attainable goals, make small changes, and track your progress on your journey toward the healthiest, most vibrant version of you!