Not sure if you've ever had migraines, but I have. Luckily I don't get them often but I know those that do (once every couple weeks, lasting for 2-3 days). Reducing the frequency is a godsend.
Dug around and found that this is a commonly reported side benefit of a ketogenic diet.
Sounds off the wall until you realize Keto diets were originally used for managing childhood epilepsy.