Being obese might be the single most important risk factor for the worst outcomes for COVID-19.

According to a review of more than 75 previously published studies that involved more than 400,000 patients, obese COVID-19 patients were twice as likely to require hospitalization and were nearly 50% more likely to die than non-obese individuals.

The more extra pounds, the higher the risk of severe disease

Even when scientists were still collecting the first data on COVID-19 patients early this year, it became apparent that obesity was a major risk factor. Not only does obesity tend to weaken the immune system, but it also is associated with diabetes and high blood pressure. However, it’s quite welcome to have all the results of dozens of studies that investigated the link between COVID-19 and obesity pooled into a single review. Unfortunately, the conclusion wasn’t encouraging for more than a third of Americans currently classed as obese.

According to the meta-analysis performed by researchers at the University of North Carolina, people with obesity were twice as like to end up in the hospital and 74% more likely to be admitted to an intensive care unit (ICU), compared to people in the normal weight interval.

Besides the fact that obesity is closely associated with diabetes and high bood pressure, both risk factors for severe symptoms of COVID-19, studies show that obesity causes high levels of glucose in the body. This affects macrophage and monocyte activation, increasing inflammation in the body. Past research has shown that macrophages from obese individuals are an ideal place for SARS-CoV-2 to thrive.

All the extra weight also puts more strain on the body’s organs and can impede breathing. Each of these individual risks adds up, making obesity one of the greatest risk factors for COVID-19, if not the single greatest one.

There are also concerns surrounding a potential vaccine for SARS-CoV-2, the coronavirus that causes COVID-19. The authors of the review caution vaccine researchers to be mindful of how a population with a high percentage of obese individuals might affect vaccine efficacy.

“The COVID‐19 pandemic challenges all countries enormously. Our systems, institutions, health and welfare will feel the impacts for many years. The high prevalence of individuals with obesity exacerbates the threat to everyone’s health, and the economic, social distancing and stay‐at‐home components compound the impacts. We will need creative solutions quickly to prevent undesirable dietary patterns and promote healthy eating, which is so critical to our future health and for building resilience against future threats,” the authors of the new study wrote.