BDNF and obesity due to melanocortin 4 receptor deficiency: Single-nucleotide polymorphisms in BDNF and its receptor TrkB are associated with obesity in humans (13–15), and BDNF is clearly involved in energy balance regulation both in the brain (where it impacts appetite and energy expenditure) as well as in the periphery where BDNF is found circulating in blood and also locally produced in tissues, such as adipose tissue stromal vascular fraction (SVF) cells (16).