The metabolic properties of cancer cells significantly differ from those of normal cells. In particular, cancer cells are largely dependent on aerobic glycolysis, a phenomenon that has been exploited clinically by using labelled glucose for positron emission tomography imaging. Importantly, cancer-associated alterations in metabolism are not merely due to the resulting response to cell proliferation and survival. Indeed, direct metabolic regulation could be driven by tumor oncogenes and/or suppressors, as demonstrated in several solid tumors, including breast cancer. Despite the fact that most breast cancer studies have focused on the intrinsic characteristics of breast tumor cells, it is now widely accepted that tumor microenvironment plays an important role in defining and reprogramming cancer cell metabolism. Tumor:stroma crosstalk, as well as inflammatory cues, concurs to outlining the cancer metabolism, impact on cancer aggressiveness and ultimately on patient survival and therapeutic responses. The aim of this review is to (i) gather the most recent data regarding the metabolic alterations in breast cancer, (ii) describe the role of tumor microenvironment in breast cancer cell metabolic reprogramming, and (iii) contemplate how targeting metabolic pathways aberrantly activated in breast cancer could help current therapeutic regimens.