The metabolic changes induced by the combination of a moderately-low carbohydrate diet combined with supplementary MCT and metformin therapy will selectively starve tumor cells. While normal brain cells are capable of deriving energy from ketone bodies during glucose restriction, tumor cells remain largely glucose-dependent for energy due to oncogene induced down-regulation of oxidative phosphorylation. While the tumor cells are in this 'vulnerable' state they will be less able to repair the damage induced by ionizing radiation.