LEP and obesity due to melanocortin 4 receptor deficiency: Consequently, SARS-CoV-2 MA can be applied to the existing mouse models to better understand the impact of COVID-19 on obesity, such as genetically obese mouse models, including leptin-deficient (ob/ob) and leptin-receptor-deficient (db/db), as well as high-fat diet-induced-obese (DIO) mouse model [275,276,277].