The present invention relates to expandable and expanded alkenyl aromatic polymer particles having the ability to use a decreased amount of blowing agent to produce an expanded alkenyl aromatic polymer particle of an equivalent bulk density or the same amount of blowing agent to produce an expanded alkenyl aromatic polymer particle having a decreased bulk density by including a density modifier in the expandable alkenyl aromatic polymer particle in an amount of about 0.005 to 0.5 weight percent by weight of the total mixture. Also included as part of the invention are methods of making the expandable and expanded alkenyl aromatic polymer particles wherein the expandable and expanded alkenyl aromatic polymer particles have a density modifier included in an amount of about 0.005 percent to about 0.5 weight percent by weight of the total mixture.