The use of dietary treatments for epilepsy (ketogenic, modified Atkins, and low glycemic index diets) has been in continuous use since 1921. These treatments have been well studied in the short term, with approximately half of children having at least a 50% reduction in seizures after 6 months. Approximately one third will attain >90% reduction in their seizures. Animal studies confirm these findings, with broad evidence demonstrating acute anticonvulsant effects of the diet. Furthermore, the diet appears to maintain its efficacy in humans when provided continuously for several years. Interestingly, benefits may be seen long term even when the diet is discontinued after only a few months of use, suggesting neuroprotective effects. This potential antiepileptogenic activity has been recently demonstrated in some animal studies as well. This review discusses the animal and human evidence for both short- and long-term benefits of dietary therapies.