I've heard "fast" as a contranym to "moving quickly," referenced as "to fast" or "fasting." ie: not eating at all. Edited to add: Sticking with the context of

I've heard "fast" as a contranym to "moving quickly," referenced as "to fast" or "fasting." ie: not eating at all. Edited to add: Sticking with the context of food, "fasting from food" contradicts someone being a "fast eater."