GHRL and obesity due to melanocortin 4 receptor deficiency: Fifteen studies reported higher basal active ghrelin concentrations in controls,16, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39 whereas seven articles found no differences between groups,40, 41, 42, 43, 44, 45, 46 and two reported higher concentrations in individuals with obesity.43, 47