Study: COVID Can Infect Body Fat Cells

COVID-19 may directly infect fat cells.

Key Takeaways

  • New research has shown that SARS-CoV-2, the virus that causes COVID-19, can directly infect fat cells as well as immune cells in fat tissue.
  • When the cells become infected, it may contribute to an inflammatory response in overweight and obese bodies with COVID.
  • Experts have offered hypotheses about what the findings could mean, but feel that more research is needed to understand the potential link between body fat and COVID outcomes.

Throughout the pandemic, data has consistently shown that being overweight and obese increases a person’s risk of developing severe COVID-19 and even dying from the virus. However, the exact reason for the increased risk has been a mystery.

A recent study has shown that SARS-CoV-2, the virus that causes COVID-19, is capable of directly infecting fat cells and immune cells within body fat, which can lead to devastating consequences.

The Stanford University study—which has not yet been peer-reviewed or published in a journal—was posted online in late October on the preprint server bioRxiv.

What Research Shows

For the study, the researchers conducted lab experiments on fat tissue that had been taken from bariatric surgery patients. The goal was to see whether the tissue could be infected with SARS-CoV-2. Then they analyzed how different types of fat cells responded to the virus.

The researchers discovered that not only could the fat cells become infected by the COVID virus, but that immune cells called macrophages—which are found in tissues throughout the body, including fat (adipose tissue)—can also become infected and contribute to an inflammatory response in the body.

When the researchers analyzed fat tissue from the bodies of patients who had died of COVID, they found SARS-CoV-2 particles in the fat that was near various organs, including the lungs and heart.

The researchers concluded that the study’s findings “indicate that adipose tissue supports SARS-CoV-2 infection and pathogenic inflammation and may explain the link between obesity and severe COVID-19.”

The new study is not the first to demonstrate that SARS-CoV-2 can infect fat cells. Research published in Cell Metabolism in September reached similar conclusions. The study’s authors wrote that the data suggested that “SARS-CoV-2 may trigger adipose tissue dysfunction to drive insulin resistance and adverse outcomes in acute COVID-19.”

Weight in the U.S.

Obesity is common in the United States, and rates are dramatically increasing. Current data show that rates in the U.S. jumped from 30.5% (1999 to 2000) to 42.4% (2017 to 2018). Severe obesity also increased from 4.7% to 9.2% during the same time.

Statistics also demonstrate that being obese affects some racial and ethnic groups more than others. Non-Hispanic Black adults have the highest rates of obesity (49.6%), followed by Hispanic adults (44.8%), non-Hispanic White adults (42.2%), and non-Hispanic Asian adults (17.4%). Some scientists attribute these differences to systemic racism.

The rates of obesity in the U.S. also vary by age: 40% in adults aged 20 to 39 years, 44.8% in adults aged 40 to 59 years, and 42.8% in adults aged 60 and older.

Weight and COVID-19

According to the Centers for Disease Control and Prevention (CDC), obesity can triple your risk of being hospitalized with COVID-19. It’s also linked to impaired immune function and decreased lung capacity and reserve. Being severely overweight can also make it more difficult to ventilate the lungs.

Data from the CDC has shown that the risk of hospitalization, intensive care unit (ICU) admission, invasive mechanical ventilation, and death were greater as a COVID patient’s body mass index (BMI) increased.

A study published in the Journal of the American Heart Association in February 2021, which included more than 900,000 adult COVID-19 hospitalizations in the U.S. from the start of the pandemic to November 18, 2020, found that about 30.2% of those hospitalizations were linked to being obesity.

BMI is a dated, flawed measure. It does not take into account factors such as body composition, ethnicity, sex, race, and age. 

Even though it is a biased measure, BMI is still widely used in the medical community because it’s an inexpensive and quick way to analyze a person’s potential health status and outcomes.

What Doctors Think

Experts are hesitant to draw too many conclusions about body fat and COVID in the absence of more data—especially since the new study is only preliminary.

“The study has not undergone peer review and has not been published in a medical journal yet,” infectious disease expert Amesh A. Adalja, MD, a senior scholar at the Johns Hopkins Center for Health Security, told Verywell.

However, Adalja added that “the study results provide a basis for possibly understanding the linkage of obesity with severe COVID; that the virus is infecting fat cells and prompting them to release inflammatory molecules.” 

Thomas Russo, MD, professor and chief of infectious disease at the University at Buffalo medical school, told Verywell that researchers already knew that some pathogens, such as influenza viruses, can infect body fat. Russo says, “if you’re obese—particularly morbidly obese—you’re more likely to have severe disease.”

Experts have hypothesized that the link is between obesity and underlying medical conditions like diabetes and chronic obstructive pulmonary disease, raising a person’s risk for severe COVID and numerous other diseases and complications.

Russo said that while the new study is “interesting and biologically plausible,” more research is needed before firm conclusions can be drawn.

What This Means For You

Overweight and obesity are known risk factors for severe COVID illness. If you are not sure how your body weight could affect your COVID risk, talk to a doctor.

The information in this article is current as of the date listed, which means newer information may be available when you read this. For the most recent updates on COVID-19, visit our coronavirus news page.

7 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Martínez-Colón GJ, Ratnasiri K, Chen H, et al. SARS-CoV-2 infects human adipose tissue and elicits an inflammatory response consistent with severe COVID-19bioRxiv. Preprint posted online October 25, 2021. doi:10.1101/2021.10.24.465626

  2. Reiterer M, Rajan M, Gómez-Banoy N, et al. Hyperglycemia in acute COVID-19 is characterized by insulin resistance and adipose tissue infectivity by SARS-CoV-2Cell Metab. 2021;33(11):2174-2188.e5. doi:10.1016/j.cmet.2021.09.009

  3. Centers for Disease Control and Prevention. Adult obesity facts.

  4. Aaron DG, Stanford FC. Is obesity a manifestation of systemic racism? A ten-point strategy for study and intervention. J Intern Med. 2021;290(2):416-420. doi:10.1111/joim.13270

  5. Centers for Disease Control and Prevention. Obesity, race/ethnicity, and COVID-19.

  6. Kompaniyets L, Goodman AB, Belay B, et al. Body mass index and risk for COVID-19–related hospitalization, intensive care unit admission, invasive mechanical ventilation, and death — United States, March–December 2020. MMWR Morb Mortal Wkly Rep. 2021;70(10):355-361. doi:10.15585/mmwr.mm7010e4

  7. O’Hearn M, Liu J, Cudhea F, Micha R, Mozaffarian D. Coronavirus disease 2019 hospitalizations attributable to cardiometabolic conditions in the United States: a comparative risk assessment analysisJ Am Heart Assoc. 2021;10(5):e019259. doi:10.1161/JAHA.120.019259

By Korin Miller
Korin Miller is a health and lifestyle journalist who has been published in The Washington Post, Prevention, SELF, Women's Health, The Bump, and Yahoo, among other outlets.