GCG and obesity due to melanocortin 4 receptor deficiency: In his review of the therapeutic effects of obesity surgery, Blasi notes the rapid and often persistent remission of type 2 diabetes and the metabolic syndrome following bariatric surgery, and reviews the major role that the vagal NTS and vaso-vagal pathways play in restoring normal function to the pancreas (normalizing insulin secretion, reducing glucagon production), liver (recovering insulin sensitivity, reducing gluconeogenesis and free fatty acid release), and gastrointestinal tract (reducing ghrelin secretion, restoring normal responses to nutrients, peptides, hormones) (Blasi, 2016).