Body Mass Index looks, at first glance, like a medical invention – a number meant to say whether your weight is “normal.” The reality is more unexpected: the formula was created in the 1830s by Adolphe Quetelet, a Belgian astronomer and statistician who had no medical training and wasn’t tracking anyone’s individual health.
Quetelet was fascinated by the idea of the “average man” – he wanted to describe an entire population statistically, not diagnose a person. His formula went medically unused for almost a century, until American insurance companies adopted it in the 20th century as a fast, cheap way to estimate risk at scale.
Only then did BMI become what we know today – a quick screening tool, statistically useful, but never intended as a precise individual diagnosis. That also explains why it ignores muscle mass, bone structure, or fat distribution.
It’s the kind of detail that slightly changes how you look at a number you already thought you knew.
See also:
–  BMI Calculator →