You’ve probably heard of BMI, Body Mass Index before. Either your doctor has mentioned it to you, you see what your BMI is on your physical print out, or you’ve calculated it yourself. BMI has been around in the medical field for a while, but what exactly is it and should we be paying attention to it?
Body Mass Index is a height to weight ratio, Kilograms over meters squared, and then falls into 4 different categories. There’s underweight (18.5 or less), healthy weight (18.5-24.5), over weight (24.6 to 29.9) and obese (30.0 and beyond). There’s even certain classes of the obese category to break down the level of obesity as well. Obese class 1 (30-34.9), Obese class 2 (35-39.9) and obese class 3 (40.0 and above).
In the clinical setting, like hospitals and some doctor’s offices, BMI is used and tracked as weight and health trend, it can be used for diagnosing things like metabolic syndrome and billing for malnutrition and obesity care, and for interventions.
However, as a dietitian, I don’t like to use BMI with my clients. Some clients will say all they want to do is have their BMI be in the healthy range, but they don’t always realize that a “healthy BMI” may not be the best measure of success.
Like I said before, BMI is just a ratio, 2 numbers are plugged in and a number is calculated. This is all subjective data and data that doesn’t even depend on the person at all.
What BMI doesn’t see is your muscle mass, muscle weighs more than fat does, so if you have more muscle that the average person, you likely weigh more than the average person.
BMI doesn’t know how you eat every day, you could be eating the healthiest and most nutritious foods out there, you could be in the best shape of your life, but your BMI is calling you overweight when you clearly are not overweight or unhealthy.
BMI doesn’t care if you put hours in the gym, have a low body fat percentage or if you have a perfect bill of health. I went to school when a guy who was very muscular, low body fat percentage and a high amount of muscle mass, but his BMI is Obese class 3! A very healthy and fit male is defined as obese class 3.
Instead of paying attention to BMI, you should really be measuring success with non-scale victories!
Start measuring your waist circumference, start seeing how your energy is throughout the day, how well your sleep is, how clear your skin is and your hunger signals. That is stuff that matters!
BMI is just a number, just like how the number on the scale is just a number. What matters more is you and how you feel. You won’t remember your BMI in one year, but you’ll remember how you feel.