Different lineages of T cells have distinct metabolic profiles. mTOR serves to coordinate differentiation and metabolism. Both CD4+ effector subsets (Th1, Th2, and Th17) and CD8+ effector T cells are characterized by a high rate of glycolysis and high mTOR activity. Conversely, naïve T cells, CD4+ regulatory T cells, and CD8+ memory cells are characterized by low mTOR activity and these cells utilize fatty acid oxidation as a source of fuel.