【成语来源】
To draw a cake to satisfy hunger
画饼充饥
Lu Yu lived in the Kingdom of Wei during the Three Kingdoms periods. He was orphaned at the age of ten.
三国时代，魏国有个叫卢毓（Lú Yù ）的人，很小的时候就失去了父母和两个哥哥。
So he undertook the task of supporting his sister-in-law and nephew through a period of extreme hardship.Meanwhile， he also studied hard. He was praised all around for his noble deeds and depth of knowledge.
卢毓从此辛苦工作，除了照顾哥哥们的家人外，自己还努力读书，受到大家的赞许。
Later he became an official and still worked hard and put forth valuable advice to the emperor， so the emperor placed great trust in him.
后来，卢毓做了官，仍然勤恳工作，经常给皇帝提出好建议，得到皇帝的信任。
At that time， the selection process of government officials depended on the recommendation of powerful and influential men.
那时候，朝廷选拔官吏，一般都是由有名望的人推荐，而推荐的人，一般又只在有名望的人里考虑。
These men would always recommend famous persons who were all mouth and no action which displeased the emperor.
其实，好多有名望的人只是嘴上能说，并不会干实际的事，因此，皇帝很不满。
One time， the emperor asked Lu Yu to recommend an official and said to him: “the selection of government officials should not rely solely on one‘s fame which is just like a cake drawn on the ground， while it may be good to look at it does not satisfy one‘s hunger.”
有一天，皇帝准备选拔一个有才能的人，并要卢毓推荐，还说选择人才不能光找有名声的人，名声只不过是画出来的一张饼，只能看，不能吃的。
This story gave rise to the idiom “draw a cake to satisfy hunger. ” Now it is used to describe someone who uses fantasy to satisfy oneself and means that empty reputation is of no practical value.
后来，人们就用这个成语比喻自己安慰自己，不能解决实际问题的方法。
【成语活用】
Your action is just like drawing a cake to satisfy hunger， which has no practical effect.
你这种做法只是画饼充饥，没有任何实际作用。