The process of cellular transformation encompasses the acquisition of key and distinctive features, commonly known as hallmarks of cancer. These hallmarks are supported by tumour-intrinsic molecular alterations as well as changes in the microenvironment. Cellular metabolism represents one of the most intimate connections between a cell and the environment. In turn, metabolic adaptation represents a research field of increasing interest in cancer biology. In this viewpoint, I will provide a panoramic perspective of the relevance and repercussions of metabolic alterations in tumours with non-exhaustive illustrative examples and speculate the prospects of cancer metabolism research.