GCG and obesity due to melanocortin 4 receptor deficiency: Moreover, bacterial supplementation with A. muciniphila led to increased mRNA levels of Peptide YY (PYY) and a significant upregulation of Glucagon-like peptide-1 (GLP-1) gene expression, both of which are intestinal hormones with appetite-suppressing, anti-diabetic, and anti-obesity properties [29].