Recently, the GLP-1/GIP co-agonist, tirzepatide, was approved by the US Food and Drug Administration (FDA) for use in patients with obesity after it was found to induce substantial weight loss in the SURMOUNT-1 trial, inducing a 19.5% reduction in weight loss compared to a 3.1% reduction in patients receiving a placebo [66]. This evidence concerns the gene GLP1R and obesity due to melanocortin 4 receptor deficiency.