In this regard, we observed an important interaction between obesity and fasting duration on hypothalamic SERT availability (F1,16 = 6.474, p = 0.022, Fig. 3D, Table 2), indicating that fasting duration differentially affects hypothalamic SERT availability in lean individuals vs individuals with obesity. The gene discussed is SLC6A4; the disease is obesity due to melanocortin 4 receptor deficiency.