SLC6A4 and obesity due to melanocortin 4 receptor deficiency: We observed no interactions between obesity and fasting on thalamic SERT (F1,17 = 0.265, p = 0.614, Fig. 3E) or striatal DAT availability (F1,17 = 1.989, p = 0.176, Fig. 3F), suggesting that the high inter-individual variation in the effects of fasting on thalamic SERT and striatal DAT availability is not explained by differences in body weight.