Food consumption is a complex act that has been the subject of studies in disciplines as diverse as epidemiology, economics, sociology, anthropology, and psychology. As Jean-Pierre Poulain points out, "various more or less implicit conceptions coexist in the world of food. They are employed both to understand how eaters are supposed to make their decisions and to influence communication strategies for economic or public health purposes." The eater can thus be considered almost entirely free in their choices and decisions or, conversely, the causes of their dietary decisions are assumed to be phenomena beyond their conscious control and, depending on the school of thought, may be determined by their physiological state, social environment, or psychological factors. [excerpt from chapter introduction]