Why Are Obese People Predisposed to Severe Disease in Viral Respiratory Infections?

Obesity is one of the most pressing healthcare concerns of the twenty-first century. Obesity prevalence has risen dramatically in recent decades, and in 2016, more than 1.9 billion adults were overweight (BMI ≥ 25 kg/m2) and 650 million were obese (BMI ≥ 30 kg/m2). About 50% of the world's population is anticipated to be obese/overweight within the next decade. Obesity is a major risk factor for a variety of non-communicable diseases, including type 2 diabetes mellitus, cardiovascular disease, non-alcoholic fatty liver disease, and a variety of malignancies. Obesity has emerged as a substantial risk factor for hospitalization and death from viral respiratory infections such as influenza A and the ongoing pandemic SARS-CoV-2. Several independent studies have indicated that obese/overweight patients are at a higher risk of severe disease and death from these respiratory diseases. Excess fat, particularly visceral fat, contributes to the development of a variety of metabolic disorders, including persistent systemic inflammation and decreased immunological function. As a result, the immunological response to infectious pathogens is weakened, resulting in poorer outcomes post-infection. Additionally, the poor lung mechanics associated with obesity may increase the risk of more serious respiratory infections. In this review, we address the likely mechanism(s) that predispose obese people to severe diseases caused by viral respiratory infections.

Obesity and COVID-19: what makes obese host so vulnerable?

The disease (COVID-19) novel coronavirus pandemic has so far infected millions resulting in the death of over a million people as of Oct 2020. More than 90% of those infected with COVID-19 show mild or no symptoms but the rest of the infected cases show severe symptoms resulting in significant mortality. Age has emerged as a major factor to predict the severity of the disease and mortality rates are significantly higher in elderly patients. Besides, patients with underlying conditions like Type 2 diabetes, cardiovascular diseases, hypertension, and cancer have an increased risk of severe disease and death due to COVID-19 infection. Obesity has emerged as a novel risk factor for hospitalization and death due to COVID-19. Several independent studies have observed that people with obesity are at a greater risk of severe disease and death due to COVID-19. Here we review the published data related to obesity and overweight to assess the possible risk and outcome in Covid-19 patients based on their body weight. Besides, we explore how the obese host provides a unique microenvironment for disease pathogenesis, resulting in increased severity of the disease and poor outcome.