West Africa has undergone rapid economic and political changes during the last 20 years. After the failure of economic policies implemented since independence, programs for structural adjustment have strongly influenced the economy. Food problems affect each country differently. The Sahel has experienced food shortages and starvation whereas in forested countries the food supply has remained stable. Nevertheless, food policies have not succeeded in contributing to urban and rural development. The rate of urbanization in west Africa is generally low but the rate of urban population growth is particularly high, much more than the growth rates of industry and infrastructure. Although metropolitan areas are affected by poverty, they offer more hope and opportunities than rural areas. Urban markets have expanded and diversified as social differences have also increased and contributed to changes in consumption structure. Urban growth has contributed to the increase of imported food: this is indicated by both the strong dependency and the change of food habits towards western food patterns. Recently however, west African urban dwellers are still preferring local items if they are affordable. When imported products are used, they are integrated within a stable meal plan consisting of a single dish with a base and a sauce, which is typical of African food preparation. Surveys of consumption-budgets are still only available on a national scale. These can provide accurate information about food consumption patterns of families, particularly for significant trends. However, they do not provide information about the dynamics of food consumption, neither for urban areas or the individual. Now a significant proportion of individual food consumption occurs outside of the home, mainly with food provided by street vendors. This new consumption habit is a response to the urban food crisis. Consumption of street-vendor-food comprises one component but this cannot be dissociated from in-home food consumption. Despite the growing importance of street-vendor food consumption, it has still not been adequately documented. Theoretically, food consumption is an evolving concept. Single disciplines, such as economics or nutrition, first studied food consumption. More recently, social sciences developed new approaches with various interpretations, which were sometimes contradictory. The evolution of urban food consumption and the numerous related problems support the approach proposed by some authors suggesting a mixed analysis integrating both economics and cultural factors. Operationally, a global and dynamic approach to food styles must consider urban heterogeneity and diversity of situations. For example, food consumption by people maintaining their in-home food habits shows the pertinence of studies focusing on individuals. Therefore, the food course concept may be a useful method for the study of food consumption. (Medline)