Various studies examined proteins, observing higher levels of several proteins in individuals with obesity, including zinc-alpha-2-glycoprotein (ZAG) [33], plasminogen activator inhibitor-1 (PAI-1) [34], calprotectin [39], chaperone activity [30], advanced oxidation protein products (AOPP) [31], and protein carbonyls (PC) [31]. This evidence concerns the gene SERPINE1 and obesity due to melanocortin 4 receptor deficiency.