fatten up give a person or animal plenty to eat, causing him or it to gain weight 长肥;养壮 * The pigs are being fattened up for market. 这些猪正在被催肥待售。 * She is fattening up the ducks. 她正在把鸭子养肥。 * I'm trying to fatten him up as fast as I can. 我在努力尽快把他养得壮实些。