GH is a lipolytic hormone. It activates hormone-sensitive lipase and therefore mobilizes neutral fats from adipose tissue. As a result, serum fatty acid levels rise after GH administration, more fats are used for energy production, and fatty acid uptake and oxidation increase in skeletal muscle and liver. GH can be ketogenic as a result of the increase in fatty acid oxidation (the ketogenic effect of GH is not seen when insulin levels are normal). If insulin is given along with GH, the lipolytic effects of GH are abolished.