The narrator tells us that he "took little interest in anything except my daily plate of soup and my crust of stale bread" (63). This is consistent with Maslow's hierarchy of needs, which tells us that we are not able to care about anything unless our basic needs for food and shelter are taken care of. The narrator has shelter, so he is reduced to his most basic need of food. He is no longer really a person at all, and describes himself as "a body," or perhaps "a starved stomach (63), meaning that he cannot care about anything except the food he needs to survive.
In Chapter 4, Elie is in a camp called Buna. He says that "all that mattered to me was my daily bowl of soup, my crust of stale bread" (page 52). Even after Elie witnesses a young prisoner being hanged and is forced to walk by the dead body and look the hanging man in the face, Elie can only think of food. He says, "I remember that on that evening, the soup tasted better than ever" (page 63). Elie is disinterested in the fate of his father, who he watches getting beaten. The concentration camp has made him so heartless that he witnesses the beating of his father and only feels anger against his father, rather than against the Kapo. Elie also befriends two boys, Yossi and Tibi, and they sing Zionist songs from their Zionist youth organization. Elie, like them, is interested in going to Palestine, and promises to get aboard a ship to Haifa if he survives past the time when the camps are liberated.