Functionalism looks at how societies form and maintain stability over time. In particular, it examine the role that institutions play in social stability. According to functionalism, cultures develop unique diets due to the competing influences of all institutions. For example, religious institutions influence diet through prohibition on certain types of food consumption. Some religious traditions within Judaism and Islam have extensive food requirements and prohibitions. Another institution that influences cultural diversity in diet is government. The U.S. government subsidizes the corn industry heavily, and this results in high corn production and consumption. Other governments subsidize different foods.
Conflict theory examines social and economic inequality within and across different communities. Conflict theory attributes cultural diversity of diet to issues of privilege, access and power. For example, traditional diets in poor nations tend to provide inadequate nourishment in terms of caloric intake and essential vitamins. On the other hand, cheap access to foods high in salt, sugar and fat has contributed to an obesity epidemic in many countries in Europe and North America.
Interactionism explains cultural diversity in terms of a community's interaction with other communities. It looks at questions of influence in cultural evolution. The Spanish diet is traditionally rich in herbs and spices. Interactionists would note that this characteristic is due to Spain's extensive interaction through both trade and conquest with Moroccan and Middle Eastern communities.