The present invention relates to a method for operating a fuel cell system, wherein the fuel cell system comprises at least one reformer for generating a reformate gas and at least one fuel cell for generating an electric current. An increased lifespan for the anode is achieved when with said anode an anode state value is continuously determined which correlates to a current degree of loading with carbon of the anode of the at least one fuel cell and when depending on the anode state value an oxygen-carbon ratio is varied in the reformate gas which is fed to the anode of the respective fuel cell.