References for this Review were retrieved by searching PubMed (MEDLINE) using the search terms: “obesity”, “physical activity”, “exercise”, “nutrition”, “diet”, “obesity pharmacotherapy”, “GLP-1 receptor agonist”, “SGLT2 inhibitor”, and “bariatric surgery” in combination with “type 1 diabetes”. Here, SLC5A2 is linked to obesity due to melanocortin 4 receptor deficiency.