GHRL and obesity due to melanocortin 4 receptor deficiency: The only three studies that analysed the leptin/ghrelin ratio were focused on the relationship with child obesity [28] and resting metabolic rate, and this ratio was considered as a possible biomarker for predicting metabolic adaptations to energy restriction treatment [22], and as a non-invasive tool for the discrimination of patients with obesity who are more likely to regain weight after therapy for obesity [29].