In 470 BCE, Duke Ai of Lu hosted a grand banquet at Wuwu, where guests clinked cups and chattered loudly—except for one man, the nobleman Meng Wubo, who sat utterly ignored.
Meng Wubo was notorious for breaking his word—he made promises only to forget them the moment they served his own interests. His habit of speaking without sincerity angered many, including Duke Ai of Lu, who openly criticized him. The duke remarked, "Wubo's words are like the wind; they come and go without leaving a trace." This story illustrates how a reputation for dishonesty can erode trust even among the highest ranks.
That day, another minister, Guo Zhong, was also present. Guo Zhong, usually favored by Duke Ai of Lu, was easygoing and portly, with a blessed appearance. Some sycophantic courtiers gathered around him, laughing and chatting to curry favor.
Meng Wubo had long harbored jealousy over Guo Zhong's imperial favor, often finding excuses to mock and humiliate him. Now witnessing this scene, his envy flared, and he couldn't resist the urge to belittle him once more.
So Meng Wubo stepped forward, parted the crowd, pointed at Guo Zhong's nose, and said, "Why are you so fat?"
Everyone present was stunned, never expecting Meng Wubo to ask such a rude question.
Guo Zhong himself was deeply embarrassed, unsure how to respond, and for a moment the air at the banquet seemed to freeze, with no one uttering a word.
Lu Ai Gong, who had long been displeased with Meng Wu Bo's character, watched all this with growing anger at his groundless provocation. Stepping in to defend Guo Zhong, he replied coldly, "He has swallowed too many promises—how could he not be fat?"
This was clearly a pointed jab at Meng Wubo's usual behavior, and the crowd, hearing it, secretly chuckled to themselves, finding it deeply satisfying.
Meng Wubo's face flushed crimson with embarrassment; he wished he could find a hole to crawl into. At such a grand banquet, before the assembled civil and military officials, he had been struck by this retort—and from the lips of the ruler himself. Truly, he had brought this humiliation upon himself, and the situation was utterly mortifying.
Later, people used the idiom "to break one's word and grow fat" to describe someone who is untrustworthy and fails to keep their promises.
Source: *Zuo Zhuan*, "Duke Ai, Year 25"
Meaning of the Idiom: Later, the Chinese idiom "食言而肥" came to describe how someone is untrustworthy and fails to keep their promises.