FASN and obesity due to melanocortin 4 receptor deficiency: Orlistat, a US FDA-approved drug, is used for the treatment of obesity by preventing the absorption of dietary fat and fatty acid synthase to reduce lipid synthesis (Kridel et al. 2004), which also significantly inhibits the infectivity of the SARS-CoV-2 virus with an EC50 of 0.39 μM in vitro (Chu et al. 2021).