The Problem With “Classes” of “Obesity"

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The entire idea of “ob*sity”* is problematic. It’s a made-up concept to pathologize bodies based on shared size rather than shared symptomology. It uses Body Mass Index (BMI) which is a math equation created with a racist basis. If your weight in pounds times 703 divided by your height in inches squared is 30 or more, you are “diagnosed” with “ob*sity.” This does not have the ring of sound science, but it gets worse.

BMI, originally pushed by the insurance industry (which sought to use it to increase profits by finding ways to deny coverage to higher-weight people,) became a part of healthcare, used as a proxy for everything from general health, to assumed behaviors, to disease risk. This ignores the fact that higher-weight people are as varied in health status and behavior as any other group of people and that the weight stigma, weight cycling, and healthcare inequalities that higher-weight people experience are correlated with those same health issues. Still, BMI is now ubiquitous in healthcare and research. Over time (and someday I’ll go into the whole sordid, diet industry-driven history of all this) “classes” of “ob*sity” were developed based on BMI.

Class 1: BMI of 30 to < 35

Class 2: BMI of 35 to < 40

Class 3: BMI of 40 or higher

The first issue is that these classifications are used to classify risk of developing so-called “weight-related” health issues. Now, “weight-related” health issues are health issues that people of all sizes get, but that get terms “weight-related” when fat people get them. And, again, that ignores the fact that those health issues are also weight stigma-related health issues, weight cycling-related health issues, unequal healthcare treatment-related health issues.

The second issue is that these classifications are used to make treatment recommendations. The healthcare system in general views higher-weight people/bodies as more risk-able (recommending more dangerous treatments to higher-weight people than thin(ner) people with the same symptoms/diagnoses. So when treatment recommendations are made based on these classifications, it typically results in those of the highest weights being given the most risky, dangerous (and expensive) treatments often focusing on weight loss for health issues that thin people also get. Recommendations around weight loss surgery and type 2 diabetes provide an example of this. In this way, the “classifications” of ob*sity serve to codify weight stigma within healthcare treatment, ensuring that the highest-weight people will have the most difficult time receiving ethical, evidence-based, weight-neutral care.

The third issue is that, well, they don’t make any sense. Going back to the recommendations for weight loss surgery and type 2 diabetes that I linked to above, less than a pound can change one’s “class” of “ob*sity” and become the difference between a recommendation to achieve glycemic management through medical options or a suggestion to have a dangerous weight loss surgery regardless of glycemic control.  

So, If you are 5’3 and weigh 225 pounds, you will receive a recommendation of behavior changes and medication for glycemic management. But if you’re 5’3 and weigh 225.75 pounds, you will receive a recommendation to have most of your stomach amputated. Again, risk is predicated on a height/weight ratio with just a .75 pound difference between recommendations with massively different risks.

The true intersection of ridiculousness and weight stigma reveals itself in “class 3.”

Note that class 1 encompasses 5 BMI points and class 2 encompasses 5 BMI points. Meanwhile, class 3 encompasses literally infinite BMI points. And doctors, researchers and other healthcare experts want us to believe that this is sound science?  

Even if we buy into the idea that the health risks higher-weight people experience are because of their height/weight ratio, and that changing someone’s height/weight ratio would reduce risk (which, again, is absolutely not settled science,) are we really to believe that the 5 point difference in BMI between class 1 and class 2 represents an increased health risk, but everyone with a BMI of 40 or above (a “class” of “ob*sity” that spans thousands of points/pounds) has the same risk?

Or perhaps it’s just that once someone gets to a BMI of 40 (which, for reference is 233lbs for someone who is a 5’4, 270.75lbs for someone who is 5’9 per the NIH BMI calculator) those making the decisions to use these classes simply don’t care about additional risks we might face because they don’t see us as worthy of care unless/until we become smaller? (And I say “us” because I’m “class 3 ob*se”)

Using these “classes of ob*sity” as if they are some kind of valid scientific/medical concept enshrines weight stigma, encourages weight cycling, and bolsters the view that the higher someone’s weight, the less valuable and more riskable they are.  The solution to this is the same as the solution to the problems with BMI in general:

We can just…let it go. And there is no need to replace it with other measurements of size or weight. Given that people of all sizes get the same health issues, we don’t need weight, size, or a ratio of weight and height, to be a middleman for health. We can simply take each patient individually and focus on supporting their health rather than manipulating their body size.

We could stop calculating BMIs for patients today and nothing bad (and plenty of good) would come of it. The diet industry could stop pouring money into studies that use questionable methods to correlate weight and health in order to sell their products. Instead, we could create research including people of diverse sizes (and diverse other identities as well) to test interventions across a spectrum of sizes, much like what was done for the COVD vaccines.

By centering the health of people of all sizes in healthcare (rather than focusing on manipulating all patients into a narrow range of height/weight ratios,) patients are afforded better care and recommended interventions that provide more benefits with far less risk.

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More research and resources:
https://haeshealthsheets.com/resources/

*Note on language: I use “fat” as a neutral descriptor as used by the fat activist community, I use “ob*se” and “overw*ight” to acknowledge that these are terms that were created to medicalize and pathologize fat bodies, with roots in racism and specifically anti-Blackness. Please read Sabrina Strings’ Fearing the Black Body – the Racial Origins of Fat Phobia and Da’Shaun Harrison’s Belly of the Beast: The Politics of Anti-Fatness as Anti-Blackness for more on this.