We've long known that obesity is linked to a higher risk of many diseases, including high blood pressure, type 2 diabetes and even some autoimmune disorders and certain types of cancer. So, it should not come as that much of a surprise that your risk of getting really sick from COVID-19 rises if you're carrying extra weight.
"While age may still be the top risk factor, research now shows that obesity is emerging as the next big one," says John Morton, MD, division chief for bariatric and minimally invasive surgery at the Yale School of Medicine.
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Throughout the pandemic, studies have showed that many of the sickest patients with the novel coronavirus were also more likely to have obesity.
In a review of 75 studies published in August 2020 in the journal Obesity Reviews, researchers looked at the medical records of almost 400,000 patients with COVID-19 and found that those with obesity were 113 percent more likely than people at a healthy weight to land in the hospital, 74 percent more likely to be admitted to an ICU and 48 percent more likely to die.
And the higher your BMI, the greater your risk in general: An August 2020 study in Annals of Internal Medicine of almost 7,000 patients with COVID-19 found that while the risk of death more than doubled for patients with a BMI of 40 (equivalent to a 5'4" woman weighing 233 pounds or a 5'9" man weighing 271 pounds) compared to those with a normal BMI, it quadrupled for those with a BMI of at least 45 (the equivalent of a 5'4'' woman weighing 262 pounds or a 5'9" man weighing 304 pounds).
Here's why a higher BMI may put you at risk, and what you can do about it.
Medical experts aren't exactly sure why obesity seems to make the novel coronavirus worse, but there are several theories.
One reason may be that obesity can cause a state of chronic, low-grade inflammation, says Fatima Stanford, MD, MPH, an obesity specialist at Massachusetts General Hospital in Boston.
"COVID-19 itself appears to be an inflammatory disorder, so when the two are combined together, it's really a perfect storm," she explains.
As a result, patients are more likely to experience a "cytokine storm" — a type of immune system overreaction where your body starts attacking its own cells and tissues rather than just fighting off the virus.
Other Chronic Conditions
It may also be because people with obesity are also more likely to have other, chronic conditions that appear to raise risk of COVID-19 complications, such as type 2 diabetes and heart or kidney disease, Dr. Morton says.
Poor lung function may be another factor.
"Obesity changes the rest of your physiology, including reduced lung volume and capacity due to too much fat around the lungs," explains Marcio Griebeler, MD, an endocrinologist at the Cleveland Clinic.
This in turn may make it more likely that you'll develop complications such as pneumonia or even acute respiratory distress syndrome (ARDS), a life-threatening condition that can occur in severe COVID-19 cases.
Obesity can make it less likely that you'll respond to COVID-19 treatment.
"It's much harder to place a person with obesity into the prone position [lying on their stomachs], which is often used in hospitals to open up airways," Dr. Griebeler says. It's also more difficult to ventilate a patient with obesity.
People with obesity also seem to carry a higher viral load of COVID-19, which means that they're not only more likely to spread the disease to others, but to experience more severe symptoms themselves, Dr. Morton says. "The COVID-19 virus has a doorway to our body through ACE2 receptors, which exist not only in our nasal, oral and lung tissue, but also in our fat tissue, as well," he explains.
But if people with obesity may be at higher risk for COVID-19, they also may be reluctant to seek medical attention if they do get sick, and the care that they do get may be inadequate.
"We know patients with obesity are less likely to seek care for even routine preventative care such as mammograms or Pap smears because of the negative interactions they have with the health care system," Dr. Stanford points out.
Doctors spend less time with patients with obesity, and are less likely to refer them for needed tests, due to strong unconscious negative attitudes and stereotypes, per a March 2015 study in Obesity Reviews.
"We know that weight stigma and bias does lead to inadequate care, so why wouldn't it be more prevalent during this pandemic?" Dr. Stanford says.
What About Vaccines?
While researchers are frantically working to find a vaccine for COVID-19, there’s also concern that it may not work as well for people with obesity, Dr. Morton notes.
“We’ve seen this in the past with other vaccines, such as the hepatitis B vaccine, since it appears that obesity can cause a decreased immune response,” he explains.
That’s why it’s so important that clinical trials make sure to include people with obesity.
What You Can Do to Stay Healthy and Safe
Follow Best Practices to Avoid Getting Infected
If you or a loved one are living with obesity, it's very important to take the novel coronavirus seriously.
"Approach the disease as you would if you were an older adult in your 60s and 70s," Dr. Morton advises.
Practice social distancing meticulously, and always wear a mask if you're around others outside of your household, even if you're outdoors. If you're not in an area with low rates of COVID-19 (that's usually defined as less than 10 cases per 100,000 people over 14 days and a COVID-19 positive testing rate of less than 5 percent) then you'll also want to limit your interactions with others and stay home as much as possible.
Consider Losing Weight
You don't have to go on a dramatic diet — in fact, that may actually backfire by depressing your immune system, which in turn may make you more susceptible to COVID-19, Dr. Griebeler points out. But focusing on a more conservative weight loss, even just 5 to 10 percent of your total body weight, may bring about big benefits.
"We know modest weight loss provides health benefits such as lowering blood pressure and improving type 2 diabetes, so it makes sense it may be protective against COVID as well," Dr. Morton says.
Adopt Healthy Habits
It's also important to embrace other healthy lifestyle habits that help strengthen your immunity: These include regular exercise, getting enough sleep, eating a heart-healthy, Mediterranean-style diet and trying to reduce stress, Dr. Morton adds.
These have the added benefit of helping you lose weight, which is a double whammy against COVID-19.
Concerned About COVID-19?
Read more stories to help you navigate the novel coronavirus pandemic:
- Obesity Reviews: "Individuals with obesity and COVID‐19: A global perspective on the epidemiology and biological relationships"
- Annals of Internal Medicine: "Obesity and Mortality Among Patients Diagnosed With COVID-19: Results From an Integrated Health Care Organization"
- Obesity Reviews: "Impact of weight bias and stigma on quality of care and outcomes for patients with obesity"
- Research Square: "The impact of previous history of bariatric surgery on outcome of Covid-19: A nationwide medicoadministrative French study"
- Obesity Society: "Obesity and COVID-19"
- Centers for Disease Control and Prevention: "Centers for Disease Control and Prevention"
Is this an emergency? If you are experiencing serious medical symptoms, please see the National Library of Medicine’s list of signs you need emergency medical attention or call 911.