Minecraft wiki entry for The_second_day, associated text: If your hunger bar is completely empty, you begin to starve, and take damage until you are down to half health in easy difficulty, or a single hit point in normal difficulty. You shouldn't be on hard difficulty for this first game, but if you are, you can actually starve to death. Well before this point (under 3.5 shanks or 7 hunger), you can no longer sprint.