The angiotensin-converting enzyme 2 (ACE2)/angiotensin 1–7/MAS axis and the gamma-aminobutyric acid (GABA)ergic signaling system have both been shown to have the dual potential to improve insulin resistance (IR) and hepatic steatosis associated with obesity in the liver. This evidence concerns the gene ACE2 and obesity due to melanocortin 4 receptor deficiency.