As the fundamental energy unit of most cells, the ATP generated from glucose is vital to maintain biological processes such as the synthesis of proteins and nucleic acids. However, a common feature of cancer cells is an altered metabolism with increased glucose uptake and the fermentation of glucose to lactate even in the presence of normal mitochondria. This phenomenon is known as the ‘Warburg effect’ (now termed aerobic glycolysis). One simple explanation for this effect is that it permits cells to more easily produce energy to support rapid growth. It can also help to meet the biosynthetic requirements for pyruvate as a major building block. As a well-known metabolic hallmark of cancer cells, the role of the Warburg effect in oncology is a newly-emerging area of growing interest. In this perspective, we provide some new understanding of these mechanisms based on recent progress in research on cancer metabolism. The better understanding of these mechanisms will support the development of new therapeutic strategies that take into account tumor nutrition and energy metabolism.