Diet-induced obesity mouse models, such as high-fat diet (HFD) feeding in C57BL/6J mice, are a well-established approach to study obesity and obesity-related complications, including systemic and peripheral insulin resistance (Surwit et al., 1998; Winzell and Ahren, 2004; Hansson et al., 2018). The gene discussed is INS; the disease is obesity due to melanocortin 4 receptor deficiency.