Role of Obesity and Smoking in Severe COVID-19 Cases

As of September 2020, over 30 million COVID-19 cases and 950,000 deaths have been reported worldwide [1]. More and more studies show that obesity and lifestyle factors, such as smoking play a role in progression and outcome of COVID-19.

Several studies showed a high frequency of obesity among COVID-19 patients admitted in intensive care [2]. Also, disease severity increased with BMI and COVID-19 patients with grade II obesity had a higher risk of in-hospital mechanical ventilation [3]. Lighter et al. found that obesity in COVID-19 patients younger than 60 years is a risk factor for hospital admission [4].

How obesity exactly influences the progression of COVID-19 is still unclear. Obesity is a major cause of type 2 diabetes mellitus, which is one of the risk factors for severe COVID-19. Diabetes is also associated with high angiotensin-converting enzyme (ACE2) expression. [5] Additionally, overweight and obesity have been continuously associated with a high risk of developing venous thromboembolism (VTE), a complication often found in COVID-19 patients admitted to the ICU. [6]

Similar results were found for COVID-19 patients that are smokers. Active smoking was associated with an increased risk of ICU admission, ventilator use and death among hospitalized COVID-19 patients. Although the exact mechanism are not clear yet, tobacco smoke can upregulate expression of angiotensin-converting enzyme 2 (ACE2), the protein used by SARS-CoV-2 as a viral receptor for cell-entry. [7, 8]

Health care professionals should take factors such as obesity and smoking into account, in order to ensure adequate treatment of COVID-19 patients.



  1. WHO. Coronavirus disease (COVID-19). Data as received by WHO from national authorities, as of 10 am CEST 20 September 2020
  2. Magdy Beshbishy, Amany, et al. "Factors Associated with Increased Morbidity and Mortality of Obese and Overweight COVID-19 Patients." Biology 9.9 (2020): 280.
  3. Simonnet A, et al. High prevalence of obesity in severe acute respiratory syndrome coronavirus‐2 (SARS‐CoV‐2) requiring invasive mechanical ventilation. Obesity (2020).
  4. Lighter J, et al. Obesity in patients younger than 60 years is a risk factor for Covid-19 hospital admission. Clinical Infectious Diseases (2020).
  5. Rao S, et al. Exploring diseases/traits and blood proteins causally related to expression of ACE2, the putative receptor of SARS-CoV-2: A Mendelian Randomization analysis highlights tentative relevance of diabetes-related traits. Diabetes Care (2020).
  6. Lorenzet R, et al. Thrombosis and obesity: cellular bases. Thrombosis research 129.3 (2012): 285-289.
  7. van Zyl-Smit R, et al. Tobacco smoking and COVID-19 infection. The Lancet. Respiratory Medicine (2020).
  8. Kashyap VK, et al. Smoking and COVID-19: Adding Fuel to the Flame. International Journal of Molecular Sciences 21.18 (2020): 6581.