Immunometabolism is an emerging field of investigation at the interface between the historically distinct disciplines of immunology and metabolism. Accelerating interest in this area is being fuelled by the obesity epidemic and the relatively recent realization that obesity affects the immune system and promotes inflammation, and that obesity-induced inflammation potentially promotes a variety of chronic conditions and diseases. The multilevel interactions between the metabolic and immune systems suggest pathogenic mechanisms that may underlie many of the downstream complications of obesity and offer substantial therapeutic promise.