Obesity affects a significant proportion of the UK population, and tirzepatide, a dual glucagon-like peptide (GLP-1) and gastric inhibitory polypeptide (GIP) receptor agonist, is increasingly being prescribed by online services as well as primary care for weight loss in both diabetic and non-diabetic patients. The gene discussed is GIP; the disease is obesity due to melanocortin 4 receptor deficiency.