In particular, a HFD led to an upregulation of genes such as toll-like receptor 4 (TLR4), NF-κB, Cd68, Emr1, IL-6, indoleamine 2,3-dioxygenase (IDO), TNF-α, and interferon gamma (IFN-γ) in rodents, suggesting that these changes were related to diet-induced changes rather than obesity. Here, IFNG is linked to obesity due to melanocortin 4 receptor deficiency.