The ketogenic diet, a diet high in fat and extremely low in carbohydrates, has recently gained momentum and is increasingly employed by patients in order to lose weight. We report a case of an otherwise healthy 47-year-old male who developed seizures and hypoglycemia shortly after initiating this diet. Biochemical testing confirmed hyperinsulinemic hypoglycemia and a subsequent abdomen MRI showed a pancreatic mass. The tumor was ultimately excised with pathology confirming an insulinoma. It was felt that his abrupt decrease in carbohydrate consumption led to the rapid unmasking of this tumor.