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In-depth: Why extra weight is such a risk factor for COVID-19

Doctors cite several physiological factors
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SAN DIEGO (KGTV) — New studies are showing that one of the most important risk factors for COVID-19 is weight, including for children.

People who are obese are more than twice as likely to wind up in the hospital with COVID-19 as those with normal weight, and 48 percent more likely to die from it, according to a study last month that looked at hundreds of thousands of patients.

“Some people have made the argument that the deaths from COVID are just in people with preexisting conditions. Well, this is a preexisting condition that affects a third of the U.S. population in the obese range and another third in the overweight range,” said Dr. Christian Ramers of Family Health Centers of San Diego. “So it’s extremely common.”

More than 71 percent of adults are either overweight or obese, according to the CDC. Adults are considered overweight if their body mass index is 25 or higher, and obese if their BMI is 30 or higher.

The U.S. has one of the highest rates of obesity in the world, and some experts have theorized it’s one of the reasons why the virus has hit our country harder than others.

The risk extends to children as well, who are generally spared from severe cases of COVID-19. Among children hospitalized with the disease, 38 percent had obesity, by far the largest risk factor, according to a CDC study.

But what is it about fat that makes the virus worse?

There are several theories. People who are obese have blood that clots more easily, one of the main ways COVID-19 kills. Fat cells secrete tiny proteins that cause inflammation, another huge problem with COVID patients that can spiral out of control in what’s called a cytokine storm.

Overall, obese people have weaker immune systems.

“The theory is that the fat is taking over in certain parts of your body that normally are producing white blood cells,” said Dr. Marsha Blount of Sharp Rees-Stealy Medical Center.

Extra fat on the abdomen makes it harder to get air into the lungs, exacerbating conditions like pneumonia. And the extra weight makes it harder to use a ventilator, said Dr. Ramers.

On top of all that, people with obesity frequently have other underlying conditions.

“Hypertension, diabetes, obesity, fatty liver -- these things are all associated with each other,” Dr. Ramers said. “What we’ve seen is that each of them is related to a poor outcome with COVID.”

Studies have shown that simply being overweight increases the risk of COVID-19. A study of nearly 17,000 hospitalized patients in the U.S. found that 29 percent were overweight and another 48 percent were obese.

The encouraging news, according to Dr. Blount, is that losing just 5 percent of your weight can have significant benefits. Dr. Blount teaches other physicians how to talk about weight loss with a technique called motivational interviewing.

“That 5 percent has been proven time and time again to decrease the risk of getting diabetes. It decreases breast cancer risk for females. It lowers triglycerides and improves HDL, which are different lipid numbers and that thereby decreases your risk of stroke and heart attack,” she said.

It can also reduce blood pressure, another major risk factor for COVID, suggesting a little weight loss can go a long way.