There are a variety of ways that probiotics or prebiotics may help reduce obesity and related metabolic disorders which include manipulation of gut microbiota by increasing SCFAs production in the large intestine, endotoxin reduction, preventing the expansion of visceral adipocytes, reducing appetite and inducing the feelings of satiety, which is linked to a plasma rise of the gut peptide concentrations (GLP-1 and PYY) [76]. The gene discussed is PYY; the disease is obesity due to melanocortin 4 receptor deficiency.