Obesity is a chronic disease that leads to an increased risk of mortality and morbidity, and the impact of the COVID-19 pandemic may create a new health challenge. There is clear evidence showing that some biological and social factors associated with obesity involve an increased risk of COVID-19 infection, hospitalization, and greater severity compared to people with normal weight. Undoubtedly, obesity involves a low-grade proinflammatory state that produces a dysregulation of the immune system that compromises its ability to respond to respiratory infection by COVID-19 and so produces a worsening of the disease. In this review, the main epidemiological and pathophysiological data that associate obesity with COVID-19 are described.