America does not have a COVID Crisis, it has an Obesity Crisis
Let's start with cold hard facts:
- People with obesity who contracted SARS-CoV-2 were 113% more likely than people of healthy weight to land in the hospital,
- 74% more likely to be admitted to an ICU, and
- 48% more likely to die.
A constellation of physiological and social factors drives those grim numbers.
A constellation of physiological and social factors drives those grim numbers. The biology of obesity includes impaired immunity, chronic inflammation, and blood that’s prone to clot, all of which can worsen COVID-19. And because obesity is so stigmatized, people with obesity may avoid medical care.
“We didn’t understand early on what a major risk factor obesity was. … It’s not until more recently that we’ve realized the devastating impact of obesity, particularly in younger people,” says Anne Dixon, a physician-scientist who studies obesity and lung disease at the University of Vermont. That “may be one reason for the devastating impact of COVID-19 in the United States, where 40% of adults are obese.” Compared to a prevalence of about 6% in China and 20% in Italy.
As patients with confirmed cases of COVID-19 first began arriving at Johns Hopkins Hospital in Baltimore in March, cardiologist David Kass heard surprising observations from his colleagues in the ICU. First, the patients were younger than expected, in light of reports from China and Italy that the virus mostly endangered the elderly. Second, many of the patients in Baltimore were obese.
Fat itself is metabolically active, and it produces a fair number of pro-inflammatory molecules called cytokines, which are a type of immune protein. It's as if your body is kind of battling itself continuously—a little war caused by signals released from fat cells which the immune system responds to, producing a low level of background inflammation. So if you are obese, this is the baseline. Now you superimpose a bigger battle with a novel virus that the immune system has not seen before, and it becomes hyper-activated. That's not going a good combination.
Another area that I believe deserves more study is the role of the ACE2 protein in fat cells. This protein is key for the COVID-19 virus, since the virus must bind to it in order to gain entry into a cell. It turns out fat cells express ACE2 at fairly high levels, and there are some past data on this idea related to other respiratory viruses that they can attack fat, last in fat, and shed more slowly from fat. This could make an obese individual more infectious even as their symptoms get better.
It has become clearer that people who are obese are one of the groups at highest risk from the disease, regardless of their age. The CDC recently refined its risk categories for COVID-19, stating that obesity was as big a risk for COVID as having a suppressed immune system or chronic lung or kidney disease. The agency also lowered the bar for where that risk starts -- from a BMI of 40 to a BMI of 30. Roughly 40% of Americans have a BMI over 30.