GHRL and obesity due to melanocortin 4 receptor deficiency: Specifically, one study showed that ghrelin increases pancreatic polypeptide secretion in individuals with obesity, but not in lean neither in obese post-RYGB subjects (Tamboli et al., 2017), whereas another study found that ghrelin-induced increase in pancreatic polypeptide is blunted by alcohol administration (Farokhnia et al., 2021).