Excess consumption serves as a motif throughout Dune to emphasize the gluttony and greed of Baron Harkonnen and many of his high class peers. Note the following example from Book 1, Part 2: 

The Baron moved out and away from the globe of Arrakis. As he emerged from the shadows, his figure took on dimension—grossly and immensely fat. And with subtle bulges beneath folds of his dark robes to reveal that all this fat was sustained partly by portable suspensors harnessed to his flesh. He might weigh two hundred Standard kilos in actuality, but his feet would carry no more than fifty of them.

In this passage, Herbert directly connects the Baron's obesity to his villainy. In a society where resources are scarce, the Baron consumes far more than he needs. He consumes so much excess that his body cannot physically handle the extra weight; the Baron is only alive and mobile because of his wealth, which permits him to access portable suspension technology. The Baron's obesity thus signifies his privilege in a world of limited resources. 

The Atreides and the Fremen also frequently meditate on excess consumption of water as a sign of greed or inhumanity—note Lady Jessica's musings on the excesses of the Atreides palace on Arrakis.