Combine flour, baking powder, baking soda, cinnamon, salt and nutmeg in a large bowl. Stir well and set aside.
In a small bowl, whisk together brown sugar, oil, applesauce, egg, egg white, and vanilla. Add to flour mixture. Mix until dry ingredients are moistened. Stir in zucchini and grape nuts. Batter will be thick.
Spray an 8x4" loaf pan with non stick spray. Spoon batter into pan. Bake for 45-50 minutes or until a wooden pick comes out clean. Cool on a wire rack.