Healthy Body

The BMI Is a Deeply Flawed Measure of ‘Health’—Particularly for BIPOC Communities

Kells McPhillips

Photo: kate_sept2004; Graphics: Well+Good Creative

Belgian mathematician Lambert Adolphe Jacques Quetelet invented what would become the Body Mass Index (BMI) in the early 19th century. The Quetelet Index he created—which works on the assumption that certain weight-to-height ratios are ideal for health—divides a given person’s weight in kilograms by their square of height in meters. His hope was to use data and statistics to determine what an “average” man should look like, and he collected data on fellow Europeans in order to “perfect” his index.

Fast-forward to 1972, when physicians were looking for a standard by which to measure obesity. Reubin Andres, MD, clinical director of the National Institute on Aging, dug up the Quetelet Index, updated it with modern population data, and christened it the BMI.

Today, over 200 countries buy into the BMI as a measure of health, where a score of 18.5 is considered underweight, 18.5-24.9 is considered “normal,”  25-29.9 is “overweight,” and a 30 or above is considered “obese.” In the United States, the Center for Disease Control and Prevention (CDC) recommends the BMI as “an inexpensive and easy screening method for weight category—underweight, healthy weight, overweight, and obesity.” Yet the “easy,” “inexpensive” route for doctors and insurance providers also forces far too many people to conform to European body types from the 19th century.

The adoption of the BMI created a ripple effect that would warp, other, and devalue the health of many people in the future, particularly Black, Indigenous, and people of color (BIPOC). In fact, Sabrina Strings, PhD, a professor of sociology at the University of California, Irvine, and author of Fearing the Black Body: The Racial Origins of Fat Phobia, believes the BMI helps very few people beyond white males.

The origins of the BMI—and how accurate it is as a prediction of health

White bodies determined what counted as a “healthy” weight even before the BMI became ubiquitous, says Dr. Strings. In 1943, the Metropolitan Life Insurance Company (MetLife) developed height-weight tables using data primarily collected from a white population. These tables classified ideal weight ranges for both men and women based on three sizes: small, medium, and large. The goal was to use these tables to calculate how long a person would likely live based on their weight, and provide life insurance coverage accordingly.

In the 1970s, Dr. Andres and other researchers resuscitated Quetelet’s index by converting those mostly-white height-weight tables to create a new set of ratios that indicated “health” (and, more specifically, a lower mortality rate). He then concluded that BMI trumped both relative weight and frame size as an indicator of health and longevity—a conversion that would have huge impacts on BIPOC communities (particularly women). “When [physicians] decided that they wanted to transition from already-biased weight tables to a new biased measure, they chose BMI,” says Dr. Strings, “even though it contains many of the same laws as the weight table in that the population for which it was developed was white.”

When she first heard about the history of the BMI, Dr. Strings wanted to believe that physicians had performed research on a racially and gender-representative population, as the BMI has evolved and changed over time (it was most recently updated in 1998). Sadly, her search came up empty. “In my research, what I expected to find was that there were some studies that were conducted using representative populations that would show, amongst those representative populations, how adiposity [or obesity] is related to health outcomes. Instead, in a lot of the early reports that use BMI, the population was largely white,” says Dr. Strings. That means that the American standards of health are inherently non-Hispanic white standards, even though research tells us that white people typically have different body types than those of Black, Latinx, Indigenous, and other people of color.

Not only is the BMI not necessarily an inclusive measure of health, but it’s also an inaccurate one. With the BMI, weight and height are the only two measurements taken to reach a conclusion on how “healthy” someone is; BMI doesn’t take into account bone density (bone is twice as dense as fat), muscle mass, nor the fact that there are four main types of body fat—not all of which are harmful to human health.

Essentially, the BMI is an inherently flawed system that serves to center a white, male, European standard of health as one that’s universal to all. Before even walking into the doctor’s office, many people’s natural bodies are deemed “unhealthy” or “healthy,” defined as such within the confines of white-centered standards.

How the BMI harms BIPOC communities in particular

BMI is often used to predict a person’s risk for certain conditions like heart disease, high blood pressure, and diabetes, but it is an imperfect measure for many BIPOC communities. For example, the high rate of chronic diseases among Black Americans has long been chalked up to obesity rates, but research shows that Black Americans are over-indexed for obesity thanks to BMI—meaning that weight might not necessarily be the cause of these disparities. George King, MD, chief scientific officer of the Joslin Diabetes Center in Boston, says that the BMI can also make doctors underestimate the health risks of many Asian people. Take diabetes risk, which is commonly associated with a BMI of 30 or higher. But for many Asian Americans, diabetes risk seems to increase “somewhere between a BMI of 23 and 25,” says Dr. King. This means that an Asian American person could be at risk of diabetes despite being at a BMI that’s considered healthy.

The BMI’s Eurocentric framing might also mean that people of color with larger bodies might be more likely to have health concerns chalked up to their weight. Starla Shines Gomez, RDN, recalls a time when her sister went to her doctor for an annual physical; her BMI and abnormal lab results—which showed an increase in blood sugar— prompted her doctor to place her on a medication for diabetes (a condition commonly associated with obesity). Since Gomez and her sister live together and eat more or less the same meals every day, the results didn’t sit quite right with the dietitian.

“I review her labs every single year,” Gomez recalls, and in previous years, her labs were normal. “This year, they came back elevated, and something was not right,” says Gomez. She encouraged her sister to go back to the office and insist her doctor look into her symptoms beyond her weight. Eventually, her physician referred her to an endocrinologist, who diagnosed her with a metabolic disorder unrelated to diabetes that may have gone untreated if Gomez’s sister hadn’t demanded better care.

Her sister’s experience, says Gomez, is just one example of an all-too-common ordeal within many BIPOC communities. “I see this over and over again—how BMI is used to control a minority woman’s body when minority women’s bodies are so different from a white male body,” says Gomez. “Many in my community and other communities of color are being told that they need to slim down, that they need to detox their bodies, they need to do all of these things to fit into [a certain BMI]. And that, genetically, they may never be able to fit in.” Not only is this dangerous for physical health outcomes, but Gomez says it’s consistently taxing on mental health as well. “You’re unable to think freely and open up your mind about other larger issues in the world—and how can you contribute to society if most of your mental power is going to controlling your body?”

Overemphasis on BMI in health-care settings can also create an environment where people of color in larger bodies may avoid or dread going to the doctor. “There’s a chilling effect,” says Dr. Strings. “There is this awareness that already indigent populations have that if they go to the doctor, they’re probably not going to get excellent care and they’re also most likely going to be stigmatized for their weight.” Indeed, research shows that people who are considered overweight or obese are more likely to avoid seeking out health care—an avoidance driven in part by the weight stigma they encounter from health-care practitioners.

Looking beyond the BMI for better health

Dr. Strings loves to dream of a future where medical care doesn’t revolve around the BMI (or weight, in general). “I’m imagining a scenario in which people go into the doctor, they present their symptoms, and then they are diagnosed without being weighed,” says Dr. Strings. (This is a tenet of the Health at Every Size ethos, a health-care philosophy that is weight-neutral.) In fact, Dr. Strings says there’s no evidence to back up the idea that one measurement of health (including the BMI) can be applied accurately to all populations, even just within the United States.

However, the road to abolishing the BMI won’t be a straight line. Dr. King says that insurance companies often ask for an individual’s BMI as a screening tool before covering certain tests and procedures, and right now, the medical community hasn’t found a clear way forward from that paradigm. However, Dr. Strings says one risky, yet possible, option would be a public refusal to be weighed at the doctor’s office at all.

“If we say that, as a society, we refuse to be weighed because this is not germane to my medical treatment, what would happen?” asks Dr. Strings. “If we had a social movement, I can’t imagine that they could have any real resistance,” she says, because unless medical providers can prove that these BMI thresholds were created using an inclusive and representative data set, then that standard shouldn’t be applied to anyone.  It’s well within your rights to refuse to be weighed (and, by extension, have your BMI calculated) at the doctor’s office.

Until the day when the BMI fades into history, many members of BIPOC communities will have to continue to advocate for their own health in the same way Gomez’s sister did. Just because the existing system chalks your health up to your height and weight doesn’t mean you have to believe it.

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