Sub-Saharan Africa is currently in the midst of an unprecedented wave of urbanization that is expected to have wide-ranging implications for food and nutrition security. Though this spatial transformation of the population is increasingly put forward as one of the main drivers of changes in food consumption patterns, empirical evidence remains scarce and the comparative descriptive design of existing research is prone to selection bias as urban residence is far from random. Based upon unique longitudinal data from the Tanzania National Panel Survey and the Kagera Health and Development Survey, this study will be the first to assess the impact of urbanization on food consumption through comparing individuals’ food consumption patterns before and after they have migrated from rural to urban areas. We find that even after controlling for individual fixed heterogeneity, baseline observable characteristics and initial household fixed effects, urbanization is significantly associated with important changes in dietary patterns, including a shift away from traditional staples towards more processed and ready-to-eat foods. While there is some evidence of changes that can be deemed beneficial from a nutritional point of view - including increased consumption of vegetables and animal source foods - the results also largely confirm concerns about the association between urbanization and heightened consumption of sugar and fats. In addition, we find no support for the hypothesis that urbanization is associated with more diverse diets. Finally, the results clearly indicate that rural-urban migration significantly contributes to reducing volatility in food consumption.