Influence of Excess Weight on the Risk of SARS-CoV-2 Infection and Hospitalization: A Case–Control Study in a Rural Area of Spain

Background/Objectives: This study aimed to examine whether excess body weight is associated with susceptibility to SARS-CoV-2 infection, and to explore its relationship with COVID-19 severity, measured as the risk of hospitalization, in a rural population in Spain. Methods: A case–control observational study was conducted in the Soria Health Area, including 236 confirmed COVID-19 cases and 243 controls without a previous diagnosis of COVID-19. In addition, a nested cohort analysis was performed among the cases to evaluate the association between excess body weight and disease severity, defined by the need for hospitalization. Bivariate and multivariable logistic regression analyses were performed to identify factors independently associated with SARS-CoV-2 infection and hospitalization. Results: Excess body weight was not independently associated with SARS-CoV-2 infection risk after multivariable adjustment. In contrast, increasing body mass index was strongly associated with COVID-19 severity. Among individuals with confirmed infection, hospitalization risk increased nearly fivefold in individuals with overweight (OR = 4.97; 95% CI: 1.75–16.22), and eightfold in those with grade I obesity (OR = 8.35; 95% CI: 2.56–29.83). The highest odds ratio was observed for grade II–III obesity (OR = 72.00; 95% CI: 6.31–820.84), although this estimate was based on a small number of events and should therefore be interpreted with caution. These associations remained significant after multivariable adjustment. Conclusions: In this rural setting, excess body weight was not linked to an increased risk of SARS-CoV-2 infection but remained independently associated with greater COVID-19 severity after adjustment for potential confounding factors. The graded association between BMI and hospitalization risk highlights obesity as a key modifier of adverse outcomes and supports preventive interventions into clinical practice for patients with excess body weight.