The ketogenic diet (KD) traditionally was initiated using specified ketogenic ratios, limited calories, and fluids. Recent work has shown that lower ketogenic ratio diets are frequently as efficacious as higher ones and result in fewer adverse effects. In animals, calorie restriction is anticonvulsant. In children, however, the need for calorie restriction is less clear, but avoidance of excessive calories may improve efficacy of the diet. There is no evidence that fluid restriction is a necessary component of the KD. Given the higher risk of nephrolithiasis, adequate fluid intake should be encouraged.