Weight and COVID-19: What Does the Research Actually Tell Us?
As usual, the association is murkier than it seems.
May 31, 2020 (SELF) – It’s deeply frustrating that we still have to worry about weight stigma—even in the midst of the global COVID-19 pandemic. From jokes about gaining the “quarantine 15,” to headlines dutifully examining the claim that fat people are “on death row,” to Nancy Pelosi taking a jab at the president by calling him “morbidly obese” on national television, the new coronavirus has seemingly opened up infinite ways to be cruel to people with higher weights.
In a culture already primed for fatphobia—often cloaked in faux concerns about health—it’s disappointing but not surprising that the association between a high weight and severe COVID-19 symptoms is already being used as fodder for weight stigma. But the research that all of these judgments are based on isn’t as conclusive as you might think. And, interestingly, while the major health authorities in the U.S. have labeled obesity as a risk factor for severe outcomes from the virus, not all countries have done so. (Canada, Australia, and the WHO do not list it as a risk factor, for instance.)
So, what does this research actually show? And, if there is a link between weight and COVID-19, what’s causing it? How can we best care for everyone right now, especially fat people who are already at risk for stigma, bias, and poor treatment from the public and those in the medical world?
What the research shows us about weight and COVID-19
Whether or not the CDC determines a particular condition to be a risk factor depends both on research we have about that factor in the context of this particular situation as well as any evidence we have for it being dangerous in similar contexts, SELF explained previously. The CDC considers obesity to be a risk factor for diabetes, heart disease, stroke, and some types of cancer, so it makes some sense that the agency would include it as a risk factor for COVID-19 as well even in the absence of a conclusive link to the new coronavirus.
And, looking at the research we have so far, multiple studies have shown an association between having a high body mass index (BMI) and developing severe COVID-19 complications. But what that association actually means—whether there is a causal link between a higher weight and coronavirus outcomes or just a correlation—isn’t clear yet, Leora Horwitz, M.D., associate professor of population health and medicine and director of the Center for Healthcare Innovation and Delivery Science at NYU Langone Health, tells SELF.
Dr. Horwitz and her colleagues published one of the earliest studies to look specifically for an association between BMI and COVID-19 outcomes. And just this past week, her team published a more comprehensive study in the BMJ of over 5,000 coronavirus patients in New York.
Specifically, they looked at data for 5,279 coronavirus patients who tested positive at facilities in NYC and Long Island. Of those patients, a little over half of them (2,791 people) were admitted to the hospital and 1,904 were eventually sent home alive. From there, the researchers looked at how strongly different risk factors were associated with being hospitalized and severe COVID-19 illness. In the study, severe illness (referred to in the study as “critical illness”) was defined as being admitted to the hospital’s ICU, requiring mechanical ventilation, being discharged to hospice care, or dying.
The strongest risk factors for both being hospitalized and having severe COVID-19 illness was age. But having heart failure, being male, having chronic kidney disease, and having any increase in BMI above 25 also increased the risk for hospitalization. Those with BMIs between 25 and 30 had a 4 percentage point increase in risk for hospitalization, those with a BMI between 30 and 40 had a 9 percentage point increase, and those with a BMI of 40 and above had a 14 percentage point increase. Heart failure, BMI over 40, and being male also significantly increased the risk for severe illness.
These results suggest that, among other risk factors, having a high BMI may increase your risk for both hospitalization due to the new coronavirus and severe COVID-19 illness. But researchers still don’t know why that might be or how important it is in the grand scheme of coronavirus-related risk factors.
The limitations and lingering questions
This association between having a high BMI and being at a greater risk for hospitalization and severe COVID-19 symptoms does seem to be consistent, Dr. Horwitz says, meaning that multiple studies have shown that people with higher BMIs—particularly those over 40—are more likely to be hospitalized and have severe coronavirus symptoms. But that doesn’t mean we know what’s driving it—or that fatness itself has anything to do with it, Lindo Bacon, Ph.D., author of Health At Every Size: The Surprising Truth About Your Weight, tells SELF
For one thing, patients could have comorbid health conditions that are difficult to separate out in the data. Several of the conditions that are known risk factors for COVID-19 are also commonly linked to having a higher weight, such as diabetes and heart disease, so it’s challenging to know if the association we’re seeing is really due to higher BMI or simply because people with higher BMIs are also more likely to be dealing with these other conditions.
In Dr. Horwitz’s study, the researchers did attempt to disentangle the effects of comorbid conditions, she says, so the links they report for BMI are meant to be related to just BMI on its own. However, Bacon and Stuart W. Flint, Ph.D., associate professor of psychology at the University at Leeds, focusing on weight stigma and discrimination, tell SELF they aren’t convinced the current evidence is enough to consider high weight or high BMI an independent risk factor.
Other confounding issues include things like race. We’ve already seen CDC data showing that people of color, particularly black and Latinx people, are at a higher risk for hospitalization and severe COVID-19 outcomes and people in those groups are also more likely to have higher BMIs. (Interestingly, in Dr. Horwtiz’s study, black patients and white patients had similar risks for hospitalization and black patients actually had a lower risk for severe illness, which suggests that data may not be reflecting trends seen in the rest of the country).
We also need to take socioeconomic status into account, especially considering it’s one of the most powerful predictors of mental and physical health status, the American Psychological Association says. And, according to CDC data, women who are in middle and lower-income groups are more likely to be obese. So if someone has a higher BMI and is also part of one of these vulnerable groups, that may be a much more important factor for their health than their weight.
That said, there are some theories about why having more fat on your body could directly contribute to worse COVID-19 symptoms, David A. Kass, M.D., director of the Institute of CardioScience at Johns Hopkins University School of Medicine, tells SELF. In a study published recently in the Lancet looking at the association between BMI and COVID-19 outcomes in young people, Dr. Kass and his co-authors suggest that the issue could be purely mechanical.
If you’re carrying more fat on your body, it can simply be more difficult to breathe efficiently on your stomach (which research suggests is the ideal position for those being ventilated with COVID-19), Dr. Kass says. This could also be why the association with severe illness is stronger for those with BMIs over 40, not just anyone who could be classified as “obese.” But, again, this is just a theory and not something that’s been conclusively proven.
Another possibility is that people who have higher BMIs also tend to show higher levels of certain markers of inflammation in their bodies, like C-reactive protein. And, in fact, in Dr. Horwtiz’s study, the level of C-reactive protein that patients had in their bodies was more strongly associated with severe illness than age or any comorbid conditions. So, the thinking is that fat people are more likely to have a hard time with the new coronavirus—or, really, any illness—because they are already dealing with higher baseline levels of inflammation. But, as SELF explained previously, that line of thinking hasn’t been totally proven and often ignores the role that mental health issues (not to mention being on the receiving end of weight stigma) also have on inflammation levels.
Ultimately, even though there does seem to be a link here, researchers don’t fully understand why. And, so far, there is no conclusive evidence that it’s the fat on people’s bodies that’s driving it. “It’s one thing to say that there is an association,” Dr. Horwitz says, “and it’s another thing altogether to understand it.”
The problem with jumping to conclusions
Not only do we not fully understand the link between weight and COVID-19 outcomes, but there are also plenty of other risk factors we know more about. And, in most cases, those seem to be more important to worry about than weight. In Dr. Horwitz’s study, for instance, age was by far the most important risk factor, she says. Being 75 or older was associated with an increase of 58 percentage points, meaning that if you had, say a 10 percent risk for hospitalization at baseline, being 75 would increase your risk to 68 percent, Dr. Horwitz explains. In contrast, having a high BMI increases your risk by 10 to 15 percent depending on the exact BMI number, Dr. Horwitz says, which was on par with the increase in risk associated with diabetes and kidney disease in her study.
Although results like these may be helpful for researchers looking into how best to triage patients and get them the care they need, we all need to take extreme care in how we think and talk about these results—especially if we’re just members of the general public. “We have to be really careful in looking at this research because we don’t want to blame the fatness and increase the stigma,” Bacon says.
So, how can we responsibly and respectfully give these associations the investigation they deserve? We can use them as a starting point, Bacon says. Knowing that there’s a higher prevalence of hospitalization or severe outcomes is important to know, they say, so that we can ask other important questions, like ‘Why is there higher prevalence?’ and ‘What role could fat stigma be playing in increasing the prevalence?’ We simply don’t have the answers right now.
Instead, as it stands now, people with higher weights are left with ambiguous media warnings about how they should be extra scared about the new coronavirus without any actual evidence-based guidance for how to effectively protect themselves, Flint says. There’s just the usual protective behaviors that we should all be doing, such as social distancing, wearing masks, and practicing good hand hygiene.
“If you identify people in a high-risk group and don’t provide information [for them], you’re increasing concern and anxiety,” he says, which is why he wrote a letter that recently appeared in the Lancet: Diabetes & Endocrinology explaining how problematic the current situation is. “The scarcity of information regarding the increased risk of illness for people with a BMI higher than 40 has led to ambiguity and might increase anxiety, given that these individuals have now been categorized as vulnerable to severe illness if they contract COVID-19,” the letter reads.
But, regardless of that ambiguity, that hasn’t stopped the media or the general public from running with it, increasing stigma as a result.
The role of fat stigma
Weight is one of many factors that researchers are looking at right now, Dr. Horwitz says, “nobody is singling out obesity as the risk to worry about.” And even on an individual doctor and patient level, “I don’t feel like the one thing we look at when we look at a patient is whether or not they’re obese,” she says.
But many fat people have experienced exactly that—an entire doctor’s appointment whittled down to weight. We know that fat people are more likely to be shamed in a medical setting and receive worse care than people in smaller bodies. Stigma like this keeps fat people out of doctor’s offices, delaying crucial medical care and potentially worsening health.
So, in order to get people in larger bodies the care they deserve, we have to work to reduce weight stigma, including being careful about how we talk about research like this. “The media need to be conscious of their role, not only in disseminating information, but also in public health,” Flint says. Politicians, Instagram commenters, and everyone else needs to pay attention as well. Pretending to care about people’s weight out of concern for their health does not help and can actually be harmful—in the context of the new coronavirus or any other issue.
Sarah Jacoby is a health and science journalist and is especially interested in the science of skin care, sexual and reproductive health, drugs and drug policy, mental health, and helping everyone find their personal definition of wellness. She’s a graduate of NYU’s Science, Health, and Environmental Reporting Program and has a background in psychology and neuroscience.
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