The coronavirus responsible for the pandemic (SARS-CoV-2) infects both fat cells and certain immune cells within body fat.
The finding comes from research led by Stanford University School of Medicine.
The findings could mean that the coronavirus is able to evade the body fat’s immune defences.
It could also explain why overweight and obese are at a higher risk of severe illness and death from COVID-19.
New research suggests that COVID-19 infects fat cells, explaining why overweight and obese are at a higher risk of severe illness and death from COVID-19.
The study, led by Stanford University School of Medicine, examined whether fat tissue obtained from bariatric surgery patients could become infected with the virus, and tracked how various types of cells responded to the virus.
It found that fat cells and also immune cells (macrophages) can be infected, leading to a 'robust inflammatory response'.
The findings show the virus is able to evade the immune defences within the body's fat cells, before causing inflammation elsewhere in the body and could help explain why patients with excess body weight are particularly vulnerable to the virus – and also why some younger adults with no underlying health issues become so ill.
The research will reinforce the importance of work being done in the health and fitness and spa and wellness industries, to help people control and reduce their percentage of body fat.
Liz Terry, editor of HCM magazine and editorial director of Spa Businessmagazine, said: "The health and fitness and spa and wellness sectors have been lobbying governments around the world to gain essential service status, so our health clubs and spa and wellness businesses can always be there to support people with their health as we grapple with the pandemic.
"Research such as this, from such an eminent source, lends weight to this argument and as we discover more about the SARS-Cov-2 virus and its many mutations, it becomes clear that our industries have a vital role to play in supporting individuals and governments to battle this challenge.
"Our sectors must continue to present evidence, such as this in, support of our bids to be recognised as essential."
In reporting the details of the findings, the researchers said: "Collectively, our findings indicate that adipose (fat) tissue supports SARS-CoV-2 infection and pathogenic inflammation and may explain the link between obesity and severe COVID-19.
"Obesity is associated with adverse COVID-19 outcomes, but the underlying mechanism was unknown.
"We demonstrate that human fat tissue is 'permissive' to SARS-CoV-2 infection – the virus that causes COVID-19 – and that infection elicits an inflammatory response, including the secretion of known inflammatory mediators of severe COVID-19.
"We identify two cellular targets of SARS-CoV-2 infection in adipose tissue: mature adipocytes and adipose tissue macrophages.
"Adipose tissue macrophage infection is largely restricted to a highly inflammatory subpopulation of macrophages, present at baseline, that is further activated in response to SARS-CoV-2 infection.
"Preadipocytes, while not infected, adopt a pro-inflammatory phenotype. We further demonstrate that SARS-CoV-2 RNA is detectable in adipocytes in COVID-19 autopsy cases and is associated with an inflammatory infiltrate.
The research has not yet been peer-reviewed, but has been published online.