This version of an apocryphal quote (attributed to many people, including William Osler and Carl Sandberg) was often repeated during my medical school education, including the start of our first lecture. The challenge, of course, is revealed in the rest of the quote — namely, that we don’t know which part it will be. Despite the quote’s repetition, we were rarely told the degree of confidence we could rely upon for each fact being shoved into our brains or how strong (or not) the evidence was behind the medicine.

Much like this quote, society and the medical system start to believe statements if they are repeated enough. It can then be challenging to unseat long-held beliefs, even after evidence is published to the contrary. What is common knowledge gets accepted as truth without questioning the underlying evidence basis or even the potential for implicit bias driving its origin.

Such as the much-vaunted BMI. The Body Mass Index (BMI) was created by a European actuary to determine the population statistics of Caucasian males. It was never intended for widespread dissemination nor clinical use.¹ BMI was never validated on the overwhelming majority of the world’s population, i.e., females and non-Caucasians, and yet it is the defining characteristic of whether someone is “sick enough” to deserve treatment coverage for multiple diseases.

For example, the DSM-5 mandates that a patient must be underweight in order to receive the diagnosis of “anorexia,” and BMI is how the severity is defined — not the presence of other factors such as bradycardia, hypokalemia or low bone density, but purely on the BMI. This bias/distinction has also spawned the fatphobic diagnosis of “atypical” anorexia, in which a patient has all the characteristics of anorexia except for low BMI.² This bias causes treatment initiation for “atypical” anorexia to be significantly delayed because of this distinction, despite the high mortality risk of eating disorders.³

In addition to the mental struggles a patient may face of not being “good enough” at having an eating disorder, insurance companies often deny coverage for things such as inpatient/residential stays or even regular dietician visits, purely due to coding F50.89 (other specified feeding and eating disorders) rather than F50.01 (anorexia nervosa, restricting type). A patient can be seen in a family physician’s office for fatigue after having lost 40% of their previous body weight through severe restriction, be congratulated for losing weight and then be told to lose more weight to treat their fatigue — true story.

Or the creation of obesity as a disease. In addition to the BMI being extrapolated from its original purpose, being considered “normal,” “overweight” or “obese” is purely based on a patient’s BMI. For example, the population map showed a stark change in 1998, when the normal/overweight cutoff was lowered from 27.8 (men) or 27. 3 (women) to 25.⁴ The change was political, as studies actually showed that higher BMI was not associated with mortality until at least 40 was used as the cutoff.^5,6 Ancel Keys, head of the Minnesota Starvation Experiment and also known food company spokesperson, was the one who advocated for BMI as the general measure of “fatness” without disclosing his conflicts of interest — after all, medicalizing someone at a higher weight opens up more opportunities to sell them weight-loss/health products! Actually, 77% of the NIH Obesity Task Force were weight-loss clinic directors,⁷ and the majority had multiple industry-related conflicts of interest.⁸

Yes, our country is getting heavier as the decades go by. Agreed — this is undeniable. There are many correlations with this increase, but we have all learned that correlation does not prove causation. We cannot prove a specific cause that lets every diet-plan sect blame their forbidden fruit of choice. We need to stop blaming individuals for our society’s changing body types. We ignore studies that show people at higher weight were more likely to have been infected with adenovirus-36 and that infecting multiple animal species with this virus led to increased weight gain and body fat without changes in their caloric intake.^9,10

We also ignore the true magnitude of the “obesity epidemic.” The CDC published in JAMA that “more than 400,000 Americans died of overweight and obesity every year, so many that it may soon surpass smoking as the leading cause of preventable death.”¹¹ The retraction, which was far less publicized, acknowledged that there were computational errors in the original study, so that “obesity and overweight were only associated with an excess of 26,000 annual deaths, far fewer than guns, alcohol, or car crashes.” In 2000, there were 86,000 fewer deaths than expected of people in the “overweight” category than if they were at a “normal BMI.” Furthermore, there were slightly more total deaths of people in the “Underweight BMI” category than those in both the “overweight” and “obese” categories.¹²

When we continue to blame the individual for a problem that is not completely a problem, we ignore the influences of social determinants of health, of racism, of misogyny. Just like healthcare institutions want to pretend that the individual physician who is burned out was not “resilient” enough rather than having to address systemic burdens, we also pretend that a person at a higher weight is “lazy” or doesn’t have enough willpower. Studies show that people at higher weights consume approximately the same amount or even fewer calories than lean people.^13-16 The myth of “calories in, calories out” is just that — a myth.