The patient population may be stratified for baseline ghrelin levels (Garcia et al, 2005; Wolf et al, 2006), and other factors need to be controlled for, namely genetic alterations of the ghrelin gene (Holst and Schwartz, 2006), cytokine levels (Dixit et al, 2004), stress level (Kristenssson et al, 2006), hypogonadism (Strasser et al, 2006), patients' eating preferences (Blom et al, 2006), baseline food intake (Gilg and Lutz, 2006), and gastric emptying (Binn et al, 2006). The gene discussed is GHRL; the disease is hypogonadism.