Remarkably, multiple clinical studies have conclusively demonstrated the efficacy of leptin in the amelioration of obesity linked to congenital leptin insufficiency (Kilpeläinen et al., 2016; Dallner et al., 2019; Lawler et al., 2020; Hanssen et al., 2023; Saeed et al., 2023). This evidence concerns the gene LEP and obesity due to melanocortin 4 receptor deficiency.