The point of this post, believe it or not, is about the choice of the word ‘fast’ to symbolize the abstention from food, drink, et cetera. Anybody who has fasted will tell you that these days feel like the slowest days of the year.
The first (of many) definitions for the word ‘fast’ is:
1 a : firmly fixed <roots fast in the ground> b : tightly shut <the drawers were fast> c : adhering firmly d : not easily freed : stuck <a ball fast in the mouth of the cannon> e : stable <movable items were made fast to the deck>
The idea seems to be indicating a firm adherence to the religious ritual of abstaining from food for a specified period. It would take willpower and firmness of resolve. Anybody who has fasted knows this quite well.