Obesity is a major risk factor for developing metabolic complications, such as diabetes. Regular exercise is an effective way to retain a healthy body weight and improve metabolic disorders. Recently, Boström P. et al. has characterized a novel hormone named by him as irisin, which is released by the exercising muscle and promotes energy expenditure in mice, via increased thermogenesis, a well recognized effect of regular exercise. Irisin achieves this effect by promoting the formation of mitochondria rich, brown-fat like cells (beige cells) in subcutaneous fat depots. In addition, adenoviral delivery of irisin to mice protected them against high fat diet induced diabetes II and obesity. Given its proven powerful antidiabetic properties irisin may be an effective future treatment against diabetes and obesity. In addition it is 100% conserved between human and mouse, and it is increased in the human plasma after exercise.In the present research proposal, we plan to identify the receptor of Irisin using the well established method of expression cloning. Furthermore, we will do therapeutic testing of exogenous forms of Irisin, delivered intraperitoneally as FC-contructs to mice fed a high fat diet. Given success we will have developed a powerful drug, ready for phase I clinical trial.