In certain aspects, the present invention provides compositions and methods for treating fatty liver disease by administering an antagonist of an ActRIIB signalling pathway. Examples of such antagonists include ActRIIB polypeptides, anti-ActRIIB antibodies, anti-myostatin antibodies, anti-GDF3 antibodies and anti-activin A or B antibodies. A variety of hepatic and metabolic disorders may be improved by treating fatty liver disease.