Preheat oven to 350 degrees. Grease an 8 by 4 by 2-inch loaf pan. In a mixing bowl combine flour, baking soda, baking powder, salt, cinnamon and nutmeg. In another bowl combine sugar, zucchini, egg, oil and lemon zest and mix well. Add flour mixture and stir until just combined. Stir in walnuts. Pour batter into prepared pan. Bake for 55 to 60 minutes. Cool for 10 minutes and remove from pan. For best results, wrap and store overnight before cutting.
