In rodents, there is a report of a relationship between BMI and P-gp; here the expression levels of P-gp in the small intestine were significantly reduced in obese rats compared with lean rats.23 This indicates that P-gp response to certain metabolites generated in obesity might be a causative factor linking high BMI to reduced P-gp expression. Here, PGP is linked to obesity due to melanocortin 4 receptor deficiency.