He said several mechanisms could explain why obesity predisposes patients with COVID-19 to severe disease.
For one, obesity places extra pressure on the diaphragm while lying on the back, restricting breathing.
“Morbid obesity itself is sort of proinflammatory,” he continued.
“Here we’ve got a viral infection where the early reports suggest that cytokine storms and immune mishandling of the virus are why it’s so much more severe than other forms of coronavirus we’ve seen before. So if you have someone with an already underlying proinflammatory state, this could be a reason there’s higher risk.”
Additionally, the angiotensin-converting enzyme-2 (ACE-2) receptor to which the SARS-CoV-2 virus that causes COVID-19 attaches is expressed in higher amounts in adipose tissue than the lungs, Kass noted.
“This could turn into kind of a viral replication depot,” he explained. “You may well be brewing more virus as a component of obesity.”
Sensitivity Needed in Public Messaging About Risks, But Test Sooner
With an obesity rate of about 40% in the United States, the results are particularly relevant for Americans, Kass and Heymsfield say, noting that the country’s “obesity belt” runs through the South.
Heymsfield, who wasn’t part of the new analysis, notes that public messaging around severe COVID-19 risks to younger adults with obesity is “tricky,” especially because the virus is “still pretty common in nonobese people.”
Kass agrees, noting, “it’s difficult to turn to 40% of the population and say, ‘You guys have to watch it.'”
But the mounting research findings necessitate linking obesity with severe COVID-19 disease and perhaps testing patients in this category for the virus sooner before symptoms become severe.
And of note, since shortness of breath is common among people with obesity regardless of illness, similar COVID-19 symptoms might catch these individuals unaware, pointed out Heymsfield, who is also a professor in the Metabolism and Body Composition Lab at Pennington Biomedical Research Center at Louisiana State University, Baton Rouge.
“They may find themselves literally unable to breathe, and the concern would be that they wait much too long to come in” for treatment, he said. Typically, people can deteriorate between day 7 and 10 of the COVID-19 infection.
Individuals with obesity “need to be educated to recognize the serious complications of COVID-19 often appear suddenly, although the virus has sometimes been working its way through the body for a long time,” he concluded.