LEP and obesity due to melanocortin 4 receptor deficiency: Leptin levels are positively correlated with obesity, which may be associated with leptin resistance, while leptin also stimulates the central pulsatile gonadotropin secretion and may trigger the timing of puberty by binding to receptors in the GnRH neurons (Ahima, Dushay, Flier, Prabakaran, & Flier, 1997; Chan et al., 2006; Fu & Zhou, 2014).