Fatty liver disease is a growing global health concern. Proglucagon-derived peptides (PGDPs), including glucagon, GLP-1, and GLP-2, are known to regulate lipid metabolism in the liver. However, the mechanism underlying this remains unelucidated. Now, researchers have investigated the role of PGDPs, including glucagon, GLP-1, and GLP-2, in fat accumulation in the liver using GCGKO mice deficient in these peptides.