Metastasizing cells undergo dynamic metabolic changes to adjust to the differing microenvironments while travelling to distant organs. Thereby, metastasizing cells can exhibit metabolic plasticity in which they use one metabolite to fuel the various metabolic requirements of the different steps in the metastatic cascade. Alternatively, they can display nutrient flexibility by using multiple metabolites to meet the same metabolic requirement imposed by a specific step of the metastatic cascade. In cancer cells, both phenomena, metabolic plasticity and metabolic flexibility, contribute to metastasis formation and may be targeted for therapy.