 Malignant gliomas have a high glycolytic rate and are dependent on glucose for energy metabolism. This so called Warburg effect or the reliance of central nervous system CNS tumor cells on glucose utilization through glycolysis has been identified as a potential therapeutic target in cancer metabolism. Preclinically, reduced cerebral glucose via calorie restriction has been repeatedly associated with tumor reduction and improved survival in glioma animal models. Such work has led to several early clinical studies evaluating the ketogenic diet KD in patients with recurrent GBM. 