Separate research fields have advanced our understanding of, on the one hand, cancer immunology and, on the other hand, cachexia, the fatal tumor-induced wasting syndrome. A link between the host's immune and metabolic responses to cancer remained unexplored. Emerging work in preclinical models of colorectal and pancreatic cancer has unveiled tumor-induced reprogramming of liver metabolism in cachexia that leads to suppression of antitumor immunity and failure of immunotherapy. As research efforts in metabolism and immunology in cancer are rapidly expanding, it is timely to discuss the metabolic and immunological determinants of the cancer-host interaction. We also present the hypothesis that the convergence of host metabolism and antitumor immunity may offer a platform for biomarker-driven investigations of new combination therapies.