text: Interleukin-15 stimulates fat oxidation, glucose uptake, mitochondrial biogenesis and myogenesis in skeletal muscle and adipose tissue. In humans, basal concentrations of IL-15 and its alpha receptor (IL-15Rα) in blood have been inversely associated with physical inactivity and fat mass, particularly trunk fat mass. Moreover, in response to a single session of resistance exercise the IL-15/IL-15Rα complex has been related to myofibrillar protein synthesis (hypertrophy).