It is also worth noticing that the most prominent anti-obesity effect of GIPR agonists as well as antagonist is accomplished in combination with GLP-1R agonists (Killion et al., 2018, 2020; Nørregaard et al., 2018; Holst and Rosenkilde, 2020) indicating an important interplay between the two incretin hormones and their receptors. This evidence concerns the gene GCG and obesity due to melanocortin 4 receptor deficiency.