How long after eating does it take for a cat's stomach to be empty? A medication my cat needs to take suggests that it be given on an empty stomach. My cats a grazer and I don`t want to starve him (he is fed every 4 to 5 hrs, and usually takes up to 1.5 hrs each meal to finish) as he`s lost a tremendous amount of weight. So, basically I`m trying to find out how long... show more A medication my cat needs to take suggests that it be given on an empty stomach. My cats a grazer and I don`t want to starve him (he is fed every 4 to 5 hrs, and usually takes up to 1.5 hrs each meal to finish) as he`s lost a tremendous amount of weight.