The 200-Year-Old Formula That Was Never Meant to Define Your Health

BMI is not a diagnosis

You've probably been reduced to a number your whole life by diets, by doctors, by the scale in your bathroom that seems to have opinions about your worth. That number has followed you to every doctor's appointment, every wellness program, every New Year's resolution that promised this time would be different.

But that number was never designed to assess individual health in the first place.

Body Mass Index (BMI), the calculation that has determined whether you're "healthy" or "needs intervention" for as long as you can remember, was created by a Belgian mathematician in the 1830s [1]. Not a physician. Not a nutritionist. A statistician who was trying to define the "average man" for sociological purposes. His sample? Western European men.

Your body is more complex than a formula that was never intended for clinical use. Your care should be too.

the history 

Adolphe Quetelet developed his index as part of "social physics," essentially an attempt to measure and categorize human variation statistically. He was looking for the characteristics of his idealized "average man," not trying to figure out whether any particular person was healthy.

The term "body mass index" wasn't even coined until 1972, when a physiologist named Ancel Keys [2] repurposed Quetelet's formula. Keys stated directly that BMI was acceptable for studying large groups of people, but shouldn't be used to evaluate individuals.

The number your doctor (including me in the past) uses to make decisions about your health was never meant for individual evaluation. However, insurance companies, pharmaceutical manufacturers, and many other players in the space use BMI as the primary way to evaluate whether a larger body is at higher risk of disease. 

The same calculation gets applied whether you're a 25-year-old athlete with substantial muscle mass or a 55-year-old woman navigating perimenopause. Whether you carry weight around your middle or your hips. Whether your family has South Asian heritage or Scandinavian ancestry. None of that gets factored in.

In 2023, the American Medical Association released a statement [3] calling BMI problematic because of "its historical harm, its use for racist exclusion, and because BMI is based primarily on data collected from previous generations of non-Hispanic white populations." In Canada, about 65% of adults are classified as overweight or obese by BMI standards, but those numbers may actually underestimate the problem.

I’m not saying we throw out measurement altogether, but it’s time to start using measurements that actually tell us something useful.

what the number misses

BMI tells you exactly one thing: the ratio of your weight to your height squared. That's it.

It can't distinguish between muscle and fat. It can't tell you where fat is located in your body. It says nothing about your blood sugar, your hormones, your heart health, or your actual risk of disease.

Research has found that nearly half of people classified as "overweight" by BMI don’t have detectable signs of organ dysfunction, though they may be at higher risk of developing it [4]. Meanwhile, about 29% of people with a "normal" BMI are metabolically unhealthy. In Canada, one study found that roughly 85% of men and 69% of women are carrying more body fat than is good for them — far more than BMI-based obesity numbers would suggest [5].

Researchers have stated it plainly: our "blanket adoption of BMI as the main indicator of obesity" has led to a "widespread, institutionalized underestimation" of who's actually at risk [6].

You could have a "healthy" BMI and still be headed toward heart disease because of where your body stores fat. Or you could have an "overweight" BMI and be doing just fine metabolically.

This is why so many accomplished women feel confused about their health. No one ever gave them the right tools to understand what their body is actually communicating, but instead made them feel like they were the problem.

where fat lives matters

Not all body fat works the same way.

The fat stored deep in your belly, wrapping around your organs, is called visceral fat. It's different from the fat under your skin on your arms or thighs. Visceral fat is metabolically active. It pumps out hormones and inflammatory chemicals that can raise your risk of heart disease, diabetes, and other problems.

BMI can't see any of this. Two people with the exact same BMI can have completely different health pictures based on where their fat is sitting.

This is why at The Shift Clinic, we use different tools depending on the care setting. For in-person assessments, I use the InBody 970, a medical-grade body composition analyzer that evaluates your body's internal ecosystem with precision. It measures segmental lean mass, body fat percentage, visceral fat area, and fluid distribution across your body. This allows me to see what's actually happening inside rather than relying on a single external number.

For virtual care, we use your waist-to-height ratio. It's simple: if your waist measurement is more than half your height, that's a sign of increased risk. Research shows this number does a better job of capturing dangerous belly fat than BMI does, and it works across different ages, sexes, and ethnic backgrounds.

the perspective shift

This connects to something bigger than measurement.

At The Shift, we use my MAP Framework: Metabolism, Appetite, and Perspective. 

Understanding how your body works is essential. But so is understanding how you see your body, and what you believe is possible.

This is where real change starts.

When you've spent decades being reduced to a number, you start to internalize it. You may see yourself as a problem to be solved rather than a person to be understood. Every weigh-in could feel like a verdict. Every fluctuation tries to confirm what you've always suspected: that you're doing something wrong, that you lack willpower, that there's something fundamentally off about you.

Stop it. You’re looking for a signal in the noise, but you’re not trained to tell the difference. 

what we actually look at

At The Shift Clinic, we take a different approach. 

We pay attention to where your body stores fat, not just how much. Belly fat tells us something meaningful about metabolic risk that total body weight simply can't.

We look at what's happening inside through the InBody 970, but also through lab work specifically examining things like how your body handles blood sugar, markers of inflammation, thyroid function, and hormone levels. We want to understand the complete picture of what's going on, not just what the scale says.

We look at your relationship with food. We call this Appetite Literacy, your ability to read your body's signals around hunger, fullness, and wanting. A lot of women have spent so long ignoring or overriding those signals that they've lost touch with what their body is actually communicating.

And we look at your life: sleep, stress, major transitions, and your history with dieting and restriction. Because lasting change doesn't happen in a vacuum, it occurs in the context of an actual human life with all its complexity.

what this means for you

If you've ever felt dismissed by a healthcare system when trying to understand weight changes, you're not imagining things. The tools most practitioners use were designed to track trends across populations, not to take care of individual people.

If you've ever been told to just "eat less and move more" without anyone digging deeper into what's actually going on in your body, that's a system failure, not a personal one.

Genuine weight care means seeing the whole picture. It means understanding that your body responds to food in ways shaped by your genetics, hormones, stress levels, and sleep. Plus much more. It means recognizing that everything is connected.

beyond the number

When you stop reducing yourself to a number, you make room for real progress. Not progress measured only by the scale but by how you feel, how you move through your day, what your relationship with food looks like, and whether your body is carrying you toward the life you actually want.

In The Shift, we think of your body as a vessel. Not defined by how it looks or what it weighs, but by its seaworthiness, which is all about its ability to carry you toward what matters to you. Your vessel needs proper care: good fuel, rest, and skilled navigation. But the goal isn't to make it look a certain way. The goal is to make it work well for you.

What we aim for is something we call Life Weight. Not a number on the scale, rather a weight range where you can live your life without spending all your time thinking about food and weight. Maintaining your health takes some effort, but we work to make sure it doesn’t feel like a constant fight. It should feel like you're cruising rather than constantly white-knuckling through choppy seas.

This is Perspective work. And it starts with recognizing that the measurements you've been using were never meant to capture the complete picture of your health.

footnotes

[1] Eknoyan, G. (2008). Adolphe Quetelet (1796–1874)—the average man and indices of obesity. Nephrology Dialysis Transplantation, 23(1), 47–51. https://doi.org/10.1093/ndt/gfm517

[2] Keys, A., Fidanza, F., Karvonen, M. J., Kimura, N., & Taylor, H. L. (1972). Indices of relative weight and obesity. Journal of Chronic Diseases, 25(6–7), 329–343. https://doi.org/10.1016/0021-9681(72)90027-6

[3] American Medical Association. (2023, June 14). AMA adopts new policy clarifying role of BMI as a measure in medicine [Press release]. https://www.ama-assn.org/press-center/ama-press-releases/ama-adopts-new-policy-clarifying-role-bmi-measure-medicine

[4] Matthias Blüher, Metabolically Healthy Obesity, Endocrine Reviews, Volume 41, Issue 3, June 2020, bnaa004, https://doi.org/10.1210/endrev/bnaa004

[5] Espinosa De Ycaza AE, Donegan D, Jensen MD. Long-term metabolic risk for the metabolically healthy overweight/obese phenotype. Int J Obes (Lond). 2018 Mar;42(3):302-309. doi: 10.1038/ijo.2017.233. Epub 2017 Sep 25. PMID: 29064474; PMCID: PMC5867190.

[6] Magkos, F. (2019). Metabolically healthy obesity: What’s in a name? The American Journal of Clinical Nutrition, 110(3), 533–539. https://doi.org/10.1093/ajcn/nqz133