We have recently shown that the activation of the transient receptor potential vanilloid subfamily 1 (TRPV1) protein by capsaicin (CAP; a TRPV1 agonist) counters high-fat diet (HFD; 60% of calories from fat)-induced obesity without decreasing energy intake [13,14] in mice housed at ambient temperature. Here, TRPV1 is linked to obesity due to melanocortin 4 receptor deficiency.