In the sixth Canto of Dante's Inferno, we arrive with Dante at the third circle of Hell, in which we encounter the gluttonous.The souls of these sinners are pelted with dirty rain, hail, and snow, which mixes with the dirt underneath to create a slimy mud, which they must eat as their nourishment. They are also watched over and tormented by Cerberus, the three headed dog, who catches them up in his mouths and eats them- constantly hungry for more.
To really get a handle on this Canto, we need to define two important words: gluttony, and contrapasso. So, gluttony is "greedy or excessive indulgence." This is most often seen in eating or drinking, but it can also refer to wealth items, like money or expensive possessions. The word contrapasso is essentially a punishment fitting the crime- something that Dante employs entirely in his construction of Hell.
The punishment that these gluttons endure is to constantly eat the putrid, slimy mud beneath their feet for all of eternity. In addition to that, the souls are devoured again and again by Cerberus- a three headed dog with a huge stomach and an insatiable hunger. Their punishment- as they were constant, indulgent consumers of the finest things in life- is to be trapped in a constant state of consuming and being consumed. In this way, their sin becomes their punishment- and so the contrapasso is created.