Changing area fill color above and below X-Axis, using drawnow

I have a GUI set up that loads a data file, and when a pushbutton is pressed, the data is manipulated and plotted using drawnow. I calculate the integral for the curve continuously and update the number, however I also want to fill in the area under the curve in the plot. The data goes above and below the x-axis, so I'd like to have it fill in, for example, red below the x-axis and green above the axis. What I have tried to do is the following:

 plot(handles.openaxes, Position(iz),Torque(iz),Position(first_turn:iz),Torque(first_turn:iz));
        if Torque(iz)<0;
            area(handles.openaxes, Position(first_turn:iz), Torque(first_turn:iz), 'FaceColor', [1 0 0]);
        elseif Torque(iz)>0;
            area(handles.openaxes, Position(first_turn:iz), Torque(first_turn:iz), 'FaceColor', [0 1 0]);
        end 
        drawnow;
        pause(0.1);(0.1);

This does start off with the right color and does switch upon crossing over the x-axis, however when it switches over, the entire plot becomes that color, not just the section I want. Any suggestions using area, patch, etc? Thanks for your help

Edit: Here is an image of the graph. The left section (-60 to -50 degrees) is what I want to show up read, as the torque is below zero.