NAMPT and obesity due to melanocortin 4 receptor deficiency: Thereby, NAD+ availability modulates the citric acid cycle, cytosolic glycolysis, gluconeogenesis, glycogen metabolism, and mitochondrial fatty acid oxidation.2 An imbalance of NAD+ homeostasis is associated with mitochondrial dysfunction, insulin resistance, and obesity.2 In line, mice on a high-fat diet showed impaired nicotinamide phosphoribosyltransferase (NAMPT)-dependent NAD+ biosynthesis in metabolic organs and an adipocyte-specific Nampt knockout resulted in severe insulin resistance, which was rescued by NMN administration.