Rodents used for obesity and metabolic experiments are commonly divided into two main categories: (a) Genetically modified rodents: animals bearing mutations in one of the key genes that regulate food uptake or the appetite/satiety cycle (e.g., leptin mutated mice) [108]; (b) DIO rodents: animals fed with a diet containing augmented amounts of fatty acids and cholesterol [109]. Here, LEP is linked to obesity due to melanocortin 4 receptor deficiency.