Overview of obesity induced changes in NK cell metabolism and function (A) in healthy individuals upon activation, NK cells increase their glycolytic metabolism mediated by mammalian target of rapamycin (mTOR), resulting in interferon (IFN)-γ production and tumor cell lysis; (B) in obese individuals, NK cells increase their expression of lipid uptake receptors (CD36, LDLR) resulting in increased uptake of free fatty acids. Upon activation, NK cells fail to activate mTOR and glycolytic metabolism resulting in decreased IFN-γ production, altered polarization of degranulation and defective tumor cell lysis.