Interleukin‐6 (IL‐6) is a central player in the regulation of inflammation, haematopoiesis, immune response and host defense mechanisms. During the last decade, an accumulating amount of data suggested a pivotal role for IL‐6 in metabolic processes, thus fortifying the picture of IL‐6 as a multifaceted, pleiotropic cytokine. Because of its secretion by adipose tissue and contracting skeletal muscle and its broad action on central and peripheral organs, IL‐6 has been termed an adipokine and a myokine. Its quantitative release from adipose tissue results in a subclinical, systemic elevation of IL‐6 plasma levels with increasing body fat content, which may be implicated in the proinflammatory state leading to insulin resistance. On the other hand, IL‐6 produced in the working muscle during physical activity could act as an energy sensor by activating AMP‐activated kinase and enhancing glucose disposal, lipolysis and fat oxidation. In addition, both impaired IL‐6 secretion and action are risk factors for weight gain. Thus, IL‐6 clearly has lipolytic effects and anti‐obesity potential. However, the application of IL‐6 itself is at least limited by a narrow therapeutic range and its important function for a balanced inflammatory response. Further studies on the molecular basis of the metabolic effects of IL‐6 could elucidate novel therapeutic strategies for custom‐designed, IL‐6‐related substances.