GHRL and obesity due to melanocortin 4 receptor deficiency: Food intake, especially amino acids, glucose but not fructose, dodecanoate, and other long-chain fatty acids, T administration, euglycemic hyperinsulinemia, impaired glucose tolerance, infusion of free fatty acids, somatostatin, cortistatin or urocortin, obesity (elevated body-mass index and increased total, subcutaneous or visceral fat), weight gain, hyperthyroidism, and leptin injection suppress ghrelin concentrations [86, 97, 116, 117, 128–144].