More Evidence That BMI Isn't a Helpful Measure of Anything

Illustration for article titled More Evidence That BMI Isn't a Helpful Measure of Anything
Photo: Glyn Kirk / AFP (Getty Images)

Health experts in England have alerted ministers to a “state of emergency” for eating disorders in the country, fueled in part by doctors’ use of Body Mass Index to identify which patients are in need of help.

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According to a briefing paper presented to the Department of Health and Social Care, and shared with the Guardian, eating disorder-related hospital admissions have increased fourfold over the course of the last year. Agnes Ayton, the chair of the Eating Disorder Faculty at the Royal College of Psychiatrists, sounded alarm bells in February, when she reported that, before the pandemic, about 20 percent of the people admitted in Oxford could be classified as urgent cases: That number has since increased to 80 percent.

And Ayton says many patients are having trouble accessing the care they need because doctors are only evaluating their health on the basis on BMI, a number determined by a person’s height and weight. Some of them—though in dire need of medical attention—had BMIs within the “normal” range, which concealed their condition.

“Unfortunately, it is not uncommon that patients are excluded from chronically underfunded services based on their BMI,” Ayton said. “This puts desperate patients in a life-threatening position to reduce more weight in order to meet the threshold to gain help.”

As far as I’m concerned, there’s more than enough evidence to conclude that BMI is complete bullshit, but the crisis Ayton describes is an important reminder that the metric can be wielded against people of all body types. When thinness is associated with overall health, doctors can overlook a thinner person’s health troubles, while insisting that a heavier person must have health problems, simply because they’re considered overweight. Doctors often fail to recognize eating disorders in overweight or obese people because they continue to be overweight; if they are losing weight, they might even be praised for achieving a “healthier” weight and BMI.

And there are a range of disordered eating and exercise habits that can present differently for different people; no single number can capture the nuance of what people are experiencing and its impact on their overall health.

“Not only does this [BMI] perpetuate the myth that eating disorders are all about weight and you can’t have one unless you weigh a certain amount, but it also fuels the eating disorder, the competition, the shame, and guilt that an individual feels.” Renee McGregor, a sports dietician, told the Guardian. “Turning people away because of their BMI [is] dangerous and costing lives.”

Night blogger at Jezebel with writing at The Baffler, The Nation, The New Republic, Vice, and more.

DISCUSSION

BMI was designed as a statistical tool for looking at populations, where the various other factors that affect ideal weight should even out. It should never be used for diagnostic purposed for individuals, because it ignores all other factors besides height and weight. Of course, it does get used a lot, because it is easy to calculate.