In certain aspects, the present invention provides compositions and methods for increasing adiponectin in a patient in need thereof by administering an antagonist of an ActRIIB signaling pathway. Examples of such antagonists include ActRIIB polypeptides, anti-ActRIIB antibodies, anti-activin A and/or B antibodies, anti-myostatin antibodies, anti-GDF3 antibodies, and anti-BMP7 antibodies. Also provided are methods for ameliorating one or more undesired effects of anti-androgen therapy, including muscle loss, bone loss, increased adiposity, and/or increased insulin resistance. A variety of disorders may be treated by causing an increase in circulating adiponectin concentrations.