Doctors are bracing for the coronavirus pandemic to meet America's obesity epidemic. Some experts worry the stigma could be dangerous by itself.

• As more people get sick and die from COVID-19, scientists and public health professionals are learning more about which populations are most vulnerable.
• Emerging research and anecdotal evidence suggests obesity may exacerbate COVID-19 symptoms, and the Centers for Disease Control and Prevention now considers "severe obesity" a high-risk condition.
• But geographical reports linking obesity rates with COVID-19 severity are faulty and, some say, stigmatizing.
• People of all sizes should take the same precautions to protect themselves, including eating a healthy diet and getting some exercise if possible within the confines of shelter-in-place and lockdown orders.
• Visit Business Insider's homepage for more stories.

Since the coronavirus pandemic began, medical and public health experts have been trying to understand why some people develop COVID-19, the disease caused by the virus, and others who are exposed have no symptoms at all.

They've also tried to pinpoint why some people with the illness find it's no big deal, while others wind up in medically induced comas and on ventilators, if not dead.

At first, data from China and Italy indicated that older people and those with underlying conditions - namely, heart disease, lung disease, and diabetes - were the most vulnerable. But then, in the US and UK, it became clear that young, healthy people could become seriously ill and die, too.

Now, as the virus hits the US hard, experts are bracing to see how it affects the unique population makeup here: With an obesity rate of 42% compared to China's 6% and Italy's 10%, some fear it could be a perfect storm.

"I worry that we are going to see a major increase in case fatality rates here in this country compared to what's been seen in some other countries in the world just because of that somewhat unique risk factor to us in the US," University of Minnesota infectious disease expert Dr. Michael Osterholm said in a March 30 interview with WCCO, a local radio station.

Jean-François Delfraissy, France's chief epidemiologist, issued a similar warning on April 8. "This virus is terrible, it can hit young people, in particular obese young people. Those who are overweight really need to be careful," Delfraissy told franceinfo radio.

"That is why we're worried about our friends in America, where the problem of obesity is well known and where they will probably have the most problems because of obesity."

Here's what the research says so far about why being in a bigger body may make you more susceptible to severe illness from COVID-19 - and why it may not.

Some reports of obese COVID-19 patients with severe disease are troubling

Anecdotal reports suggest a disproportionate percentage of the COVID-19 patients in a severe condition are overweight or obese.

Dr. Robert Eckel, president of medicine and science for the American Diabetes Association, told Business Insider that a "sophisticated internist" in New York City told him at least 90% of the people under age 50 he's seen ventilated due to COVID-19 were obese.

Fatima Fakhoury, a weight-inclusive registered dietitian in New York, told Business Insider a colleague in Cornell's surgical intensive-care unit, told her "every one" of her 60 ventilated patients in a single day, whether 28 or 85, was obese. "Call it anecdotal," Fakhoury said, "but these are real people" reporting the findings.

Some studies back up such experiences in the field.

A report out April 8 from the Centers for Disease Control and Prevention found that 48.3% of all patients admitted to the hospitals in 99 counties across the US were obese, and 59% of the 18- to 49-year-olds who were hospitalized were obese. That's startling compared to 40% of 20- to 39-year-olds in the general population who have obesity.

One not-yet-peer-reviewed study in the Lancet, made available April 1, found the same in China. Looking at 383 COVID-19 patients in China, researchers found that people who were overweight had an 86% higher likelihood or developing severe pneumonia than their normal weight counterparts. Those who were obese were 2.4 times more likely to develop it.

Higher-weight men were particularly at risk, with those who overweight almost twice as likely to develop the condition and those who were obese 5.7 times more likely.

"Those are really stunning odds ratios," Dr. Gregory Poland, an infectious disease expert at the Mayo Clinic, told Business Insider.

As such, the Centers for Disease Control and Prevention has listed "severe" obesity, or a body mass index of 40 or over, as high-risk condition for the illness.

We can't entirely trust current data linking obesity to COVID-19 deaths

A caveat to the conversation about obesity and the coronavirus is that the data is spotty, as it has been across the board since this pandemic began just a few months ago.

New Orleans has a staggeringly high death rate from the virus - twice that of New York City and four times that of Seattle - and doctors have suggested the city's obesity rates may be a factor, according to Reuters.

That doesn't appear to match up with each city's obesity rates, though. New Orleans had an obesity rate of 31.4% in 2010, the last year Business Insider was able to find data. In Seattle, 27% of people were classified as obese in 2009, while 22% of New York City residents are obese.

The same discrepancies have been seen elsewhere. In Louisiana overall, data show 25% of patients who have died from COVID-19 were obese - a lower proportion than the state's obesity rate of 36.2 percent. A study in the UK found that 127 of 196 COVID-19 patients who were in intensive care were overweight or obese. That's about 65%, almost exactly the same percentage seen in the general population.

But doctors don't need data to be concerned about high obesity rates

Medical professionals don't need geographic data to tell them America's obesity epidemic is a problem going into the fight against the coronavirus.

Public health researchers have been warning about rising obesity levels across the US for decades. It's a complicated issue, fueled by poverty and lack of healthcare access, and burdened by a stigma. It's driven a rise in the rate of Americans with heart disease, diabetes, and hypertension - comorbidities that are, in turn, connected to serious COVID-19 complications.

Obesity is especially prevalent among non-Hispanic black people - a group already suffering health disparities from the virus - affecting 49.6% in the US.

Some 18.5% of 2- to 19-year-olds are obese in the US. More than 42% of Americans in every state are obese, with the highest rates in the South, which is expected to be worst-hit for myriad reasons.

"If obesity is another independent risk factor that puts people at higher risk ... it's a pandemic in its own right," Eckel said.

Heart disease and diabetes - conditions linked to obesity - appear to increase the risk of death from COVID-19

BMI, a ratio of weight to height, is an imperfect metric of health. Someone with a "healthy" BMI who eats junk food and smokes is less healthy than someone who's technically obese but eats a plant-based diet and manages stress through exercise. But in many cases, high BMI is linked to other health conditions, such as diabetes, hypertension, and heart disease.

And those conditions are all risk factors for serious illness or death from COVID-19. A report on patient characteristics from Italy's National Institute of Health, released on March 17, found that 76.1% of patients who died from COVID-19 had hypertension, or high blood pressure, and 35.5% of COVID-19 patients who died had diabetes. Data from rge CDC found that 32% of patients in in the ICU with the virus had diabetes.

Weight gain or excess fat, particularly around the belly, is responsible for 60 to 70 percent of cases of hypertension, or high blood pressure, researchers estimate.

Experts aren't sure why people with cardiovascular conditions are are at a higher risk of dying from the virus, but doctors believe that the strain COVID-19 puts on the lungs may burden the heart as well. People with heart issues may also have weaker immune systems, and the virus could have a negative effect on those with plaque in their arteries, according to the American Heart Association.

Diabetes is another condition that's closely tied with weight: 90% of people with type 2 diabetes are overweight or obese. The condition may make COVID-19 worse because some viruses thrive on higher blood glucose levels, and people with diabetes also have compromised immune systems, according to Health.com.

Excess weight can burden the immune and respiratory systems, regardless of underlying conditions

Even people who are overweight or obese and who don't have an underlying condition like diabetes or high blood pressure may be more susceptible to COVID-19 and more severe complications. That's in part because excess weight can impact the immune system and lung function.

"At the immunological system level, the human body is extremely poorly adapted to chronic caloric overload," Poland said. "It's as bad for our immune system as malnutrition is."

Particularly among people who carry their body fat around the middle, obesity can activate inflammation and weaken the body's anti-inflammatory response, making them more susceptible to illness, research suggests.

Extra weight around the chest and in the belly can also physically restrict breathing, which can be dangerous with a respiratory condition like COVID-19.

"Prior to COVID-19, we already knew that obesity is a risk factor for infection in general and more severe complications, and this is particularly true for respiratory infections," Poland said.

During the 2009 H1N1 epidemic in 2009, adults with body mass indexes over 30 were 3.1 times more likely to die from the infection than people of lower weights, while adults with body mass indexes over 40 were 7.6 times more likely to die.

Some say warnings about obesity are unnecessary, and will only serve to heighten obese Americans' stress levels

Some dietitians, psychologists, and eating disorder specialists say that there isn't sufficient data on obesity as a COVID-19 risk factor, and that saying so can do their health more harm than good.

"There's no reason to further stigmatize higher-weight people, who are already a stigmatized group in our society," Christy Harrison, a registered dietitian and host of the Food Psych podcast, told Business Insider. "And, in fact, there's strong evidence that weight stigma increases people's risk of all kinds of diseases by putting physical stress on the body and psychological stress on the person, regardless of their actual body size."

But others say it's helpful to consider weight a risk factor, just like age is.

"It's a difficult situation and an emotional situation since people who are in a certain BMI range are discriminated against. They're right to feel attacked and marginalized," Fatima Fakhoury, a weight-inclusive registered dietitian in New York, told Business Insider. "But in this case, as one example, if somebody in a couple is obese and somebody is not, they both need to be aware that one of them is high risk, and so maybe take extra precautions."

People at higher weights should take the same precautions as any potentially vulnerable population - not go on a restrictive diet

People of all sizes should follow similar precautions to protect themselves and their communities: Stay home if possible, practice physical distancing when you must go out, practice excellent hygiene, clean surfaces frequently, and quarantine yourself if you do get sick.

Eat a healthy diet and get some exercise outdoors if possible, and prioritize good sleep and stress management. What you shouldn't do is go on a diet diet or over-exercise, since both behaviors can weaken the immune system.

"Take care of yourself ... and treat yourself with compassion," Harrison said. "This is a traumatic time, and we're all just doing the best we can."

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