Allegretti and colleagues reviewed mouse studies suggesting that the gut microbiota influences obesity by altering anorexigenic hormones such as glucagon-like peptide 1 (GLP1) and bile acids, impacting lipid metabolism Their double-blind study demonstrated that fecal microbiota transplantation (FMT) capsules obtained from lean donors were well-tolerated and induced lasting changes in the gut microbiome and bile acid profile akin to those of lean donors, ameliorating obesity-related health concerns [19]. Here, GCG is linked to obesity due to melanocortin 4 receptor deficiency.