BMI is B.S. and the scale is a pretty deceitful character too.
In order to prove my point, I volunteer as tribute...
When I was 29, I decided that I wanted to have a better understanding of my body composition and went in to get a hydrostatic body composition analysis done. This is where, more or less, you strip down to a bathing suit, submerge yourself in a tank, expel all the air out of your lungs, and walk out with a nice little printout that tells you everything from your lean body mass to your body fat percentage.
Now, here's the part where I get real vulnerable and tell you all my body stats and in return, you promise not to judge me because you appreciate my transparency, deal?
- I am roughly 5 feet tall (5' 1/2" by some accounts).
- On this particular day in 2013, I weighed 147lbs.
- My hydrostatic test results told me that my body fat percentage tested at 26.81% (No judging!)
- In order to reach "the ideal body fat percentage for women" (22% for my age according to their chart), the report said I would need to lose 9.07lbs of fat (or in other words, weigh about 138lbs).
- At 147lbs, my BMI clocked in at 28.7 classifying me as overweight and probably quite literally one carefree vacation away from being classified as obese. (After playing with a BMI calculator, I was able to determine that gaining 7lbs (weighing 154lbs) would have officially classified me as obese, a BMI of 30+.)
Now, full disclosure: Once upon a time, I WAS extremely overweight and most definitely had a BMI weeeellllll over 30. But that was many years prior and here at 29 years old, I was feeling pretty good about myself. I was doing CrossFit, eating decently, and while I clearly wasn't rocking the body of a Regional's athlete or anything, I certainly wouldn't say I looked or was physically borderline obese. In fact, I had tons of energy, felt amazing and strong, and thought like I *kinda-ish, maybe-sorta* looked like some sort of an athlete. So seeing that my BMI had me classified as almost obese was quite terrifying. Not only because I had been there once before and never wanted to go back, but also because I know there is the potential for some serious health complications that are associated with having that much extra fat on your body. But let's not get ahead of ourselves...
Let's really take a look at this whole BMI calculation by doing some math together:
- According to my hydrostatic test, I would have needed to lose 9lbs and weigh 138lbs to have been at an ideal weight (assuming my lean body mass didn't change).
- According to the BMI, someone of my height would need to weigh no more than 127lbs to be at an ideal weight and not classified as overweight. In order to obtain this, I would have needed to lose at least 20 lbs.
- But remember - my hydrostatic test said I only needed to lose 9 pounds of fat and weight 138lbs to reach an ideal body fat percentage (and thus, a healthy weight), NOT 20lbs! Ya'll, that's an 11lbs discrepancy between my hydrostatic body composition results and BMI results!!!!
- If you consider that The American Heart Association defines obese as meaning that "you are 20% or more above your ideal weight" (1), then the discrepancy between these two numbers is even more staggering.
The problem with BMI, is that it doesn't take into account things like an individual's muscular build. It's simply a ratio between your height and weight. And for athletes, who tend to have a more muscular build, this can be incredibly misleading since BMI will tend to overestimate an athlete's body fat. Moral of the story - don't place too much weight on your BMI (no pun intended). For athletes, it's pretty much B.S. and it's not worth getting all worked up over because it's almost guaranteed to overestimate your body fat.
Now let's discuss another little liar: the scale.
I can't tell you how many times I have heard others (and myself) express frustration about how they are busting their butts in the gym, eating healthy, but still aren't losing any weight. But I can look at them and totally see a change in their appearance - they simply LOOK like they have lost weight. Then how is it possible the scale isn't in alignment with what can so easily be seen?
Again, it often comes down to muscle. A pound of muscle and a pound of fat weigh the same (obviously - they both weigh a pound!). However, the physical space that a pound of muscle takes up on a person's body is much less than a pound of fat. "In fact, one pound of fat is roughly the size of a small grapefruit; one pound of muscle is about the size of a tangerine." (2) If you are working out and building muscle, there's a chance you will look and measure smaller as you lose fat, but dense muscle development might make it so the scale doesn't change much (or at all, or it might even show that you are gaining weight! #GAINZ).
Let's revisit my hydrostatic experience:
About a year after my first hydrostatic test, I went in for a second to test to see if I had managed to make any changes to my body composition. I wasn't particularly hopeful though because, admittedly, I hadn't been as consistent or diligent about my fitness or eating habits as I would have liked. In fact, I knew that according to my home scale, my weight was slightly up over the previous year.
But to my delight, my new hydrostatic evaluation produced some encouraging data. On this day in 2014, my weight was slightly up (149.4lbs as compared to the previous year, 147lbs) BUT I had gained over 4lbs of muscle and my body fat percentage had dropped to 25.18% (previously 26.81%). Sure, these are small improvements, but THEY ARE improvements. Had I allowed the number on the scale to dictate how I felt about my progress, I would have been terribly discouraged (since technically I was gaining weight) and it probably would have been detrimental to my motivation.
What I want you to take away from this is... please DO NOT allow your BMI or weight alone to define your physical health (or more importantly, self-worth!). As you can see, particularly for athletes, there are plenty of limitations to these measurements. And if you are like me and can easily be discouraged by what certain health markers might indicate, you might want to consider other ways of measuring your progress or physical health.
- Take progress photos.
- Take measurements with a measuring tape.
- Have a particular shirt and/or pair of pants that you occasionally try on to see how they fit differently.
- Go get some sort of body composition analysis done like a hydrostatic test or dexascan.
- Ask yourself: How you feel? Do you have lots of energy? Do you feel good? Do you sleep well? Do you have a positive outlook? Do you feel motivated? Do workouts feel easier? Are you lifting more? Getting faster?
And most importantly, try not to focus on what a silly number tells you, be it BMI, a scale, or even things like body fat percentage. You are SO MUCH MORE than just a number.