The pathogenesis of cancer anorexia is complex and multifactorial. However, a number of consistent and robust evidence point to a prominent role for the central nervous system. In particular, the hyperactivation of the immune system, due to tumour growth, causes a systemic inflammatory response primarily mediated by pro-inflammatory cytokines. At the central level, inflammatory response profoundly alters the activity of the hypothalamic nuclei, which are involved in the regulation of energy homeostasis. In particular, pro-inflammatory cytokines inhibit prophagic neurons activity, while enhance the activation of the anorexigenic neurons. Although supported by compelling experimental evidence, it should be acknowledged that this pathogenic hypothesis has not been confirmed yet by human studies.