Leptin concentrations are associated with obesity types, either characterised by leptin resistance (high leptin levels) or by leptin deficiency (low leptin levels) [23] and thus, it is crucial to know the underlying cause of the condition to decide on the most appropriate course of action; therefore, classifying the type of obesity based on circulating leptin levels could provide support to decide on the best therapy, as well as providing insights into its efficacy. Here, LEP is linked to obesity due to melanocortin 4 receptor deficiency.