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.