The Body Mass Index

Quetelet's Index

Adolphe Quetelet, a Belgian statistician, developed what we now know as the Body Mass Index (BMI) as part of his broader work on social physics. He aimed to identify patterns in human behavior using state-collected data, such as height and weight, to define an "average man" as a standard of perfection 1. Quetelet's index was never intended for individual health assessments but rather as a population-level tool 1. Aubrey Gordon explains, "He envisions the index being used by the state to help predict the size and shape of the population as a whole."

The average man was defined mathematically, absolutely, as sort of, like, the center of a bell curve, no question.

--- Aubrey Gordon

Despite its initial purpose, Quetelet's work laid the groundwork for future misuse of the BMI in individual health contexts 2.

   

Insurance Influence

Insurance companies played a pivotal role in transforming the BMI from a population tool to a means of individual assessment. By the mid-19th century, American life insurance companies began using height and weight tables to charge higher premiums to policyholders deemed overweight 3. This practice led to the creation of various tables, each with different standards, which were eventually standardized with the MetLife table in 1942 3. Aubrey Gordon notes, "A bunch of different insurance companies create a bunch of different tables, and then the sort of industry as a whole realizes that they should probably standardize them."

Some doctors actually start to use the insurance charts as guidelines for their individual patients, which is truly fucking wild to me.

--- Aubrey Gordon

This shift marked the beginning of BMI's widespread use in medical settings, despite its origins as a non-medical tool 4.