The BMI Trap: A Better Way to Measure Health

“I wish I was as fat as the first time I thought I was fat” 😆

Looking at this picture, I still feel as young and spry as this college co-ed. Believe it or not, I felt fat and was in a constant battle with the scale. (I’m in the center with the grey t-shirt).

For those of you who are still wrestling with the scale in search of lower number, stop!
This post is for you.

That number on the scale tells us far less about our health than we once thought.

The number on the scale is just a number. 

Back in the good old days, I attended the University of Missouri, “Mizzou” and was fortunate to be part of the Golden Girls, a high-profile dance team. It was a wonderful experience, but I will never forget how much I disliked our weekly weigh-ins.

Though I was the same size, sometimes smaller, than the other girls, I always weighed more. I remember scratching my head at the scale wondering why I struggled with meeting my weight goals while others didn’t. It wasn’t until decades later that I finally understood why. I carried more muscle than most of my GG mates and muscle weighs more than fat.

I’m sharing this because the struggle with the scale is so prevalent for so many of us. Thankfully, science is finally catching up to what many health professionals have suspected for years. As our understanding of health has evolved, researchers have shifted their focus from asking, “What do you weigh?” to asking, “What is that weight made of, and how is your body functioning?” That distinction changes everything.

BMI – An Outdated Tool 

I stopped obsessing about my weight ever since my GG days. Since becoming a fitness professional, I have become increasingly aware how outdated the BMI scale is all together. 

Did you know the BMI reference was not created by a doctor? It was created in 1830 by a Belgian statistician who was trying to define the statistical average man, using data collected from smaller, less nourished bodies than most of us have today. Obesity guidelines were set in 1994 and have not been meaningfully updated since.

Since then, so much has changed in reference to our body composition:

• The benefits of regular exercise were starting to gain acceptance in the 1960s. Until then, experts questioned whether vigorous exercise might be unhealthy!
• Sarcopenia, age-related muscle loss wasn’t even named until 1989
• Muscle has only recently been recognized for its role in longevity and overall health.

Though a 2025 University of Florida study called BMI a deeply flawed predictor of health, many healthcare institutions and insurance companies still rely on it as a measure of health risk.

The world has changed. Our bodies have changed. Our understanding of health has changed dramatically. The BMI scale has not. 

The Scale Can Stay the Same While Everything Changes

For those of us doing all the right things, exercising, eating healthy, hydrating and still not seeing the number on the scale budge…This is the message I want everyone to hear. 

A stronger, more functional body does not always weigh less. Our bodies can be losing fat, gaining muscle, lowering blood pressure, improving blood sugar, and building bone density all at the same time, and the number on the scale may barely move. Sometimes it goes up.

Weighing more can mean you are gaining muscle. Muscle matters because it:

• Regulates blood sugar
• Supports metabolism around the clock
• Protects joints and posture
• Predicts how well we recover from illness, injury, or surgery
• Fights sarcopenia before it starts

Without regular strength-building activity, adults typically lose 3% to 8% of their muscle mass per decade after age 30, with the rate accelerating after age 60.

Being strong is not about being bigger. It is about having the infrastructure that keeps us healthy, independent, and resilient for the long haul.

And every single Mojo class works on this. 

Frailty Hides in Small Bodies

Most of us grew up with the idea that smaller was healthier. Though very few of us spend much time thinking about frailty, it’s one of the biggest predictors of lost independence as we age, and it has nothing to do with dress size.

A woman can be slender by every conventional measure and still have low muscle mass, poor balance, and weak grip strength. None of that is visible from the outside. The scale won’t catch it. BMI won’t catch it. But it will absolutely shape quality of life in ways no clothing size ever could.

The Numbers Worth Knowing

Most of us know our weight. Many of us know our clothing size. But here are the numbers researchers say actually tell the story of how we are aging:

• Muscle mass percentage
• Resting heart rate
• Grip strength
• Cardiovascular fitness
• Balance

Every single one of these improves with consistent training (Mojo anyone?). Every single number tells a more telling story than anything the scale can offer.