BMI is BS
Body Mass Index says you’re obese. This expert says ignore it.
I was devastated.
Rewinding about 30 minutes…here’s what happened. I sat on the cold, firm chair in the doctor’s office but I sat up straight waiting for Dr. C to walk-in any moment. The nurse already visited for my vitals and initial intake. I was excited to talk to Dr. C. Since my last visit I improved my exercise regimen and adopted a fresh, nutritious eating plan; my life had changed for the better, and I knew it! Gleaming with confidence and pride, I couldn’t wait to hear congratulations for all the hard work I put into my health. There is a knock at the door and Dr. C walks inside. He started with the usual niceties and then he says “Jenn, your body mass index (BMI) is still concerning. According to the chart, you are obese.” My heart sank. The gleam dimmed. Confidence broken. I was devastated.
OBESE?! How can that be possible? Of course, there were days scouring the pantry for chips or the freezer for ice cream — but obese?! What about my more consistent workouts? What about all the new green foods I was eating and drinking? Dr. C didn’t offer any suggestions that I wasn’t already doing! Everything else he said was a blur as I couldn’t stop thinking about this label, obese. Walking out of the doctor’s office, on my way home, I unleashed an internal scream: “This is BS!”
For a moment that felt so isolating, this situation happens to way too many of us! I know because I’ve heard about it from virtually every client over the last 13 years. And in all irony, my conclusion of “BS” was right on the money.
BMI actually is BS, and this is why…
When a doctor tells us we are severely over or underweight, they base this on our Body Mass Index which is a calculation using our height, weight, and sometimes age. The greatest sticking-point in the whole process is that 2 out of 3 of the parameters we can’t change — at least not easily (or by much)! Therefore, we are left with only one remaining parameter, the number on the scale, to be our sole tool to change our BMI. But the total number on the scale consists of multiple components and is misleading when interpreted as a direct correlation to obesity.
Body Mass Index (BMI) was created in the mid-eighteen hundreds by the Belgian astronomer, statistician and sociologist, Lambert Adolphe Jacques Quetelet, who wanted to create a way to measure health in populations. It was deemed inappropriate for individual evaluation. Nevertheless, fast forward to present day, doctors are using this method on a patient-by-patient basis to measure “thick or thinness” instead of a true gauge of whether we are actually healthy.
This begs the question: what do we study to decide if we are healthy humans? I recommend we look at body fat percentage.
It’s a misconception that muscle weighs more than fat — a pound is a pound! However, the space taken-up by a pound of fat is far greater than the space taken-up by a pound of muscle. This means, someone with more muscle could look much smaller than someone with more fat — even though the number on the scale could be the same. Provided they are the same height and age, their BMI would also be the same. But as we know, excess fat on the body has negative implications for our overall health.
For example, a 5’6’’ woman who weighs 158 lbs. could still be considered obese despite her healthy lifestyle. Our true health is based on this ratio between fat and muscle. But the BMI calculation does not consider this ratio. At all.
This is crucial to understand when going about gauging our health for one specific reason. When we don’t understand what our BMI is telling us, and follow it blindly, we turn to fad diets that are impossible to sustain. Remember, with BMI the only component we can change is the total number on the scale. So, we restrict our calories, cut out whole food groups, which can cause weight loss in the short term. This weight loss, however, is not the fat you intended on dropping, but rather muscle and water. This creates an unhealthy result that we were completely trying to avoid in the first-place. To exacerbate the issue, because what we did to lose the weight isn’t sustainable, we return to old eating habits, gaining the weight back. Adding insult to injury because we now have less muscle on our bodies to burn this additional fuel, we gain the weight back as fat. This, by the way, is the yo-yo cycle: lose the weight as water and muscle, gain it back as fat, lose the weight as water and muscle, gain it back as fat. Over time, we might be the same weight we were before but by body composition we are actually fatter and yet the BMI would be the same. Measuring body fat percentage would be a better indicator of health as it accounts for this counterproductive cycle.
So how do we calculate our body fat percentage? There are four main ways to do this.
1. Hydrostatic weighing. While this is the most accurate way to measure, it is difficult and can be costly. It involves submerging your body in a large tank of water to calculate the exact amount of body fat. Typically, this requires a healthcare professional, potentially insurance approval and more obstacles which prohibit us from using this method regularly and widely.
2. Body weight scale with abilities to measure body fat. I recommend this tool the most. Some at home scales involve hand bars, while others require damp feet. Follow the instruction manual precisely and you will be on your road to success!
3. Calipers. These are plastic or metal clamps that pinch about an inch of skin/fat on various parts of the body, typically the side of your abdomen, under your shoulder blade, and your inner thigh. This method is accurate in terms of its absolute measurement. However, from measurement to measurement the room for human error is tremendous: we must measure the exact same location, with the exact same amount of pinching pressure, to be able to properly measure progress. Therefore, this method is more challenging to use and count on its accuracy.
4. Rule of thumb: every inch removed from waist measurement is approximately equivalent to removing 1% body fat. Your waistline is one of many measurements you might want to track, anyway. This is not the most accurate method but is a simple way to gauge progress over time.
Regardless of which method you employ, it is important to focus on the change from one reading to the next, rather than the “set in stone” number. This allows us to focus on the progress toward our optimal health and certainly uses a more accurate metric than focusing only on the total number on the scale.
And while we focus on lowering body fat percentage you’re dying to know the numbers we want to reach. I see you…Typically for women, an active and healthy range of body fat percentage is 25–32%. Above 32% body fat is considered obese. For men, the healthy range is 14–17%, the obesity level is 25% and higher.
So now you know BMI is truly BS. We will measure body fat percentage instead. Still, this knowledge is simply the beginning. We must implement this knowledge to have it make a difference.
On a bigger scale, the fight for more accurate measurements of health is just beginning. It begins with you. The next time you go to the doctor, ask them if they have a way to measure your body fat percentage — such as a higher quality scale like the one mentioned above. Get your own scale that measures body fat percentage at home and ask your doctor to document your percentage in your medical records. As patients, we must be our own health advocates and as such, what we repeatedly ask of our doctors can influence the system.
As for myself, that day I walked out of Dr. C’s office completely devastated, prompted my individual research. For that, I will be forever grateful. I bought a scale that measures fat percentage, had challenging conversations with my health care providers, and ultimately set out on a mission to pay it forward. I share my learning with my clients every day and now with you. Here’s to you, wellness warrior, for making yourself and your health a priority. You deserve it and you are worth it!
