Symbolism, Imagery, Allegory
Like snow and the cold, food is like another character in this book. And aside from worrying about keeping warm, food is the primary concern of a zek. Shukhov spends the bulk of the book thinking about food: planning what he's going to eat and when, scheming to get more food, longing for good food, worrying about bad food, etc. This total fixation on food really helps to emphasize the horrible conditions in the camps, where zeks barely get enough food to survive. Food also helps to tell us a lot about our different characters. The way characters eat, and what they eat, are all important tools of characterization in the book.