BMI: A 200-Year-Old Math Problem That Can’t Handle Your Quads | The FIT Facility
Let’s talk about the Body Mass Index — or as I like to call it, the Boring Misinterpretation Indicator. For the everyday MVP — you, the adult who lifts weights, trains hard, eats decently, and occasionally flexes in the mirror when no one’s looking — BMI might not just be wrong. It might be laughably off. Like trying to measure horsepower with a bathroom scale. Or judging your strength based on your shirt size at Old Navy.
But before we torch it entirely, let’s give BMI its due.
What is BMI anyway?
BMI is a simple equation: weight (kg) divided by height (m²). That’s it. No nuance. No context. It doesn’t care about how much muscle you have, how hard you train, or if your glutes could crack walnuts. It just sees mass and height, and throws you into one of four buckets: underweight, normal, overweight, or obese.
It was created in the 1830s by a Belgian statistician who — get this — wasn’t even a doctor. He was trying to measure trends in populations, not individual health. Somewhere along the way, we started using it like gospel for individual health. Not ideal.
It’s like using the same training program for a 13-year-old volleyball player and a 42-year-old dad who just PR’d his trap bar deadlift.
Same math.
Same mistake.
Why it fails for people who lift
You lift weights. You build muscle. You’re carrying more lean tissue than the average person binge-watching Netflix with a family-size bag of Flaming Hot Cheetos. So when a height-weight ratio like BMI looks at you, it doesn’t see the difference between a 220-pound strongman and a 220-pound couch dweller. It just sees "overweight." Or worse — “obese.”
Obese. As if your squat-heavy posterior is a liability instead of an athletic power plant.
The problem is BMI doesn’t differentiate between fat mass and lean mass. It lumps muscle and fat into one bucket and says, “Too heavy.” That’s like saying a Ferrari and a rusted-out pickup are the same because they both weigh 3,000 pounds.
But here’s the twist: it’s not total garbage
As much as we like to dunk on BMI in the fitness world, here’s where we give it a reluctant nod — for most sedentary adults, BMI isn’t a terrible starting point. It’s a blunt tool, but sometimes blunt tools get the job done. If someone isn’t training, doesn’t track nutrition, and has no clue what a goblet squat is, their BMI probably gives a semi-reasonable signal about health risk.
And here’s where we separate signal from noise: BMI trends in populations do correlate with risk factors like cardiovascular disease and diabetes. If 1,000 people have a BMI over 30, a bunch of them are probably dealing with health issues.
But if you have a BMI over 30 and you’re dragging sleds, hammering power primers, have thick slabs of athletic muscle and throwing sandbags around like Thor on leg day — you're not the population.
You’re an outlier.
You’re the one who confuses the doctor during your checkup. (“Hmm… technically obese, but resting heart rate is 52 and blood pressure is pristine? Must be a glitch in the Matrix.”)
So what should everyday MVPs use instead?
Here’s a wild idea: context.
Body composition (body fat % via InBody, Dexa, or skinfold calipers) tells us way more than BMI.
Waist circumference is a decent proxy for visceral fat.
Strength-to-bodyweight ratios (e.g., can you do chin-ups? How’s your deadlift?) give us insight into relative strength.
Energy, sleep, bloodwork, performance, recovery — these are the real health metrics.
Your value isn’t in a ratio cooked up before the invention of the lightbulb.
It’s in how you function.
How you feel.
How you perform.
TL;DR: Train, Don’t Conform
If you’re an adult who trains with intention, eats to fuel your goals, and takes care of your body — BMI isn’t your enemy. It’s just irrelevant noise. Let the general population use it as a red flag. You’ve graduated to better metrics.
Keep building your athletic armor. Keep stacking plates and protein. And if the BMI chart calls you overweight,
smile politely… then go deadlift it.
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