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Study shows link between weight loss from bariatric surgery and COVID-19 severity.

Entering 2022, worldwide COVID cases have topped the 290 million mark, with more than five million deaths (1). While new variants develop with lower mortality rates, the risk of severe COVID infection is still greater for some groups. Common risk factors include people over sixty-five, people with diabetes, chronic kidney disease, suppressed immune system, chronic lung disease, or obesity (2).

Obesity is abnormal or excessive fat accumulation. A body mass index (BMI) of over thirty is considered obese (3). The rates of obesity around the globe have almost tripled since 1975, and childhood obesity is quickly becoming a world health problem (4). 

Since the COVID-19 pandemic began, researchers have identified a link between obesity and severe COVID-19 infection. It is thought that the systemic inflammation and immune dysfunction linked to obesity can cause a more severe COVID infection (5). However, researchers were not sure whether weight loss would affect that severity (5). 

Researchers from the Cleveland Clinic recently performed a study to determine whether substantial weight loss from bariatric surgery was associated with improved risk and severity of COVID infection (5). Their results were published in the journal JAMA Surgery.

The research team used data from the Cleveland Clinic Health System. The team identified patients who underwent bariatric surgery, either a gastric bypass or a sleeve gastrectomy between January 2004 and December 2017. To qualify, the patients had to have a BMI of 35 or greater. Patients with other pre-existing medical conditions were not included.

For comparison, the team selected three times the number of patients from the same data that had not undergone any type of bariatric surgery. The control group of patients were also in the same age and BMI range. There were 5053 patients in the surgical group and 15,158 patients in the control group. 

Researchers statistically analyzed the data. The team took several approaches to looking at the data, examining weight loss and causes of death for each group before the pandemic and during the pandemic. 

Pandemic data was assessed for positive for COVID infection, hospitalization, need for supplemental oxygen, and severe COVID infection (5). A severe COVID infection was defined as one in which the patient needed ICU care, mechanical ventilation, or died (5).

The team found that before the pandemic, the surgical group had lost 20.8 percentage points of body weight versus 2.3 percentage points of body weight in the control group (5). Once the pandemic began, both the surgical and control group were at a similar risk for contracting COVID. However, improved outcomes were seen in the surgical group when compared to the control group (5).

The surgical group fared better than the control in each of these categories: 49% less likely to be hospitalized, 63% less likely to need supplemental oxygen, and 60% less likely to develop severe COVID infection (5).

In a press release study author Steven Nissen, M.D., Chief Academic Officer of the Heart, Vascular, and Thoracic Institute at the Cleveland Clinic said, “…the current study support the reversibility of the health consequences of obesity in the patients with COVID-19. This study suggests that an emphasis on weight loss as a public health strategy can improve outcomes during the COVID-19 pandemic and future outbreaks or related infectious diseases. That is a very important finding considering that 40% of Americans have obesity.”


  1. World Health Organization. WHO COVID-19 dashboard. Published 2021. Accessed January 4, 2022.
  2. Affairs (ASPA) AS for P. Who is at High Risk for Serious COVID-19? Published February 18, 2021. Accessed January 4, 2022.
  3. World Health Organization. Obesity. Published 2021. Accessed January 4, 2022.
  4. World Health Organization. Obesity and overweight. World Health Organization. Published June 9, 2021. Accessed January 4, 2022.
  5. Aminian A, Tu C, Milinovich A, Wolski KE, Kattan MW, Nissen SE. Association of Weight Loss Achieved Through Metabolic Surgery With Risk and Severity of COVID-19 Infection. JAMA Surgery. Published online December 29, 2021. doi:10.1001/jamasurg.2021.6496

Image by Vidmir Raic from Pixabay 

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