Various methods are provided for metathesizing a feedstock. In one aspect, a method includes providing a feedstock comprising a natural oil, heating the feedstock to a temperature greater than 100° C. in the absence of oxygen, holding the feedstock at the temperature for a time sufficient to diminish catalyst poisons in the feedstock, and, following the heating and holding, combining a metathesis catalyst with the feedstock under conditions sufficient to metathesize the feedstock.