To bite off more than one can chew means to take on more than one can deal with, to attempt to do something that one is not capable of accomplishing. This phrase is also employed in the warning don’t bite off more than you can chew, meaning don’t take too much work or responsibility upon oneself. Related phrases are bites off more than one can chew, bit off more than one can chew, bitten off more than one can chew, biting off more than one can chew. The idiom originated in America during the late nineteenth century when a man offered another man a bite of his plug of chewing tobacco. The admonishment don’t bite off more than you can chew would remind the receiver not to be greedy.
The Red Prince: Did apple growing pioneer bite off more than he can chew in Canada? (The Financial Post)
Shark Bites Off More Than It Can Chew, Chokes On Sea Lion (The Huffington Post)
“Obviously, as he got deeper into the training and he got further down the line, he saw how much is involved in this and I think he realised he bit off more than he can chew,” Pendred said. (The Herald Sun)
Saying the President “bit off more than he can chew” with his plan to reform the insurance system, the Ohio Republican blasted Obama for “another broken promise.” (The New York Daily News)
You can stabilize your personal life if you don’t bite off more than you can chew. (The Bowling Green Daily News)
There’s biting off more than you can chew, and there’s last night’s episode of The Good Wife, which took a run at issues of institutional racism and the police killings of Michael Brown and Eric Garner and ended up smashing into a wall. (The Atlantic)