Monounsaturation is a subcategorization of unsaturation. It refers to the state of a lipid's double bonds. An unsaturated lipid is a hydrocarbon molecule containing a double bond somewhere among its hydrocarbon chain. A monounsaturated lipid contains only one double bond. The action this double bond performs to alter the chemical structure of the lipid relates cis and trans confirmations. The double bond will lock the lipid in a trans confirmation, bending it upwards. This bend impedes the Vand der Waals forces that line up saturated lipids in fibrous structures. Monounsaturated lipids are less dense and more liquidy than saturated lipids, but have more consistancy than polyunsaturated lipids.