Obesity and COVID-19 death are linked by a hormone
Obesity has been referred to as the “parallel pandemic,” and a growing collection of research shows that excess weight is an independent and causal risk factor for mortality among COVID-19 patients. Now, a new study has traced this seemingly complex link to something as simple as a hormone that influences the body’s immune response.
The hormone leptin not only regulates appetite and metabolism, but also manages the cells that fight infection. Leptin is produced by fat cells and is secreted into the bloodstream. People with more fat have higher levels of leptin circulating in their body.
Study lead author Dr. Candida Rebello is a postdoctoral researcher at the Pennington Biomedical Research Center.
“The problem for people with obesity is that their leptin levels are always high, and that can affect the response to a COVID-19 infection,” said Dr. Rebello.
According to Dr. Rebello, elevated leptin levels hamper the body’s ability to fight off infections, in the lungs and elsewhere. High leptin levels promote inflammation throughout the body.
“If you have obesity, there are a number of underlying health issues that make it more difficult for you to fight off a COVID-19 infection,” said study co-author Dr. John Kirwan. “Your entire body, including your lungs, may be inflamed. Your immune response is likely compromised, and your lung capacity reduced.
“Add in a virus that further weakens the body’s ability to fight infection, that can limit the body’s ability to control lung inflammation, and you have the recipe for disaster.”
The findings suggest that the immunocompromised state associated with obesity must be taken into consideration for the development of COVID-19 vaccines in the same way that older age is accounted for.
“The multifaceted nature of obesity including its effects on immunity can fundamentally alter the pathogenesis of acute respiratory distress syndrome and pneumonia, which are the major causes of death due to SARS-CoV-2 infection,” wrote the researchers.
The study is published in the International Journal of Obesity.