Broke Beyond Belief:Deconstructing Institutionalized Normality and Expectations in the BMI Index

[Anonymous]

Many have probably heard the often mentioned point that goes something along the lines of "the BMI is inaccurate because it does not take into account muscle" or something of that nature. Few are likely aware of the broader issues with the BMI which go beyond this point and indict its use in the strongest terms. Here I will give a brief overview of the flaws of the BMI as an index, and their implications.

The BMI is defined as (weight/height^2)*703. The basic formula illustrates one of the most obvious flaws with such a measurement, being that there is no anthropometric reason for squaring height or multiplying the product by 703, both are essentially random mathematical modifications to the underlying data. The original concept for such a measurement dates to the 19th century Adolphe Quetelet, but was not coined as such until 1972. In any case, the formula itself is an entirely random combination, and is no more distinct than height*weight! or weight^height or any other conceivable mathematical combination.

The usefulness of the BMI supposedly lies in its "indexing" that is, regardless of the actual number it can be made useful as a relative comparison. This is superficially a satisfying explanation for some of the above, but fails when the "comparison" component comes into play. Most would think the BMI is comparing to the existing population, but in fact it is based on data collected some 50+ years ago at the minimum. When for example, someone says that a person's BMI is in the 85th percentile for their age group, they are not referencing the actual age group of the person in question, but the age group of what is likely to be their grandparents generation.

This incongruity, which is virtually never disclosed, has led to the BMI being toted as a tool of "normalization" in which ingrained power structures seek to set expectations for what an "acceptable" body is based on false pretenses. Many a person has been told that they are "fatter than their peers" when in fact they are in the middle of the bell curve. The implication being that they will be made a social outcast or pariah for their appearance if they do not conform to the "accepted" figures provided on the chart.

To illustrate this point, it is worth considering what would a "modernized" BMI chart look like if it were based on modern data. To answer this question I have applied the CDC data for a more recent decade to the problem, formatting the chart in the same fashion as percentile BMI charts are usually done. The result is a dramatic re-aliment of expectations.

A BMI Chart using modern data

Those who have been involved with the body positivity movement before will recognize the direction of the argument here, but parts of it bear repeating.

As the movement to accept and promote all bodies as desirable and valid has grown, so has the backlash and often emotionally violent rhetoric of those determined to resist this change. Chief among their tools of oppression has been a resort to so called "health" arguments, intended to both confuse the issues and legitimize their hateful rhetoric.

The BMI has naturally become a focal tool for this purpose, as a way to de-legitimize certain body types by appealing to institutional authority and establishment science. In the BMI is a mixture of bad science, misleading data, and dishonest purposes that can be used to resist social progress and change. Likewise, a metric that may have otherwise been discarded due to irrelevance (as have MANY so called "sciences" that pre-date the civil rights movement) has been given a new birth as a tool of oppression at the hands of multi-billion dollar iron triangles of ingrained interests.

To give a full view of such interests is outside the scope of this short note, but it is worth considering that these events have been beneficial to government agencies and private organizations, both looking to create the next public health problem to "solve" after the decline in smoking rates was achieved. It has also been windfall for corporations promoting what has been described as "the dominant anti-fat ethic of sport and physical activity" as a way to cash in on growing concerns fed by marketing and government funded searches for problems to solve. For these interests, the BMI has proven useful indeed.

This short note on a pressing issue of our time will hopefully prove insightful to some, but unfortunately a challenge to closely held prejudices and assumptions of others. Nevertheless, we must endeavor to keep the discussion of this topic respectful to the values of those who are trying to build a better, more tolerant world.