The investigators propose to offer this study to patients with newly diagnosed glioblastoma multiforme (GBM) that undergo gross total resection (GTR) or subtotal resection (STR) of their tumor. Post-operatively, these patients and their families will be instructed in the implementation of the Ketogenic Diet (KD) and it will be started as soon as possible following surgery to achieve ketosis and reduction of blood sugar. Patients will receive standard chemoradiotherapy with fractionated external beam radiation (60Gy) and concurrent oral temozolomide chemotherapy followed by 12 adjuvant cycles of temozolomide chemotherapy on a standard dose schedule. Outcome measures of the study group will be compared to historic controls in the treatment arm from the European Organization for Research and Treatment of Cancer (EORTC) temozolomide study published by Roger Stupp et al, New England Journal of Medicine, March 10, 2005.