Preheat your oven to 350°F (175°C). Grease a 9x5 inch loaf pan.
In a large bowl, whisk together the flour, baking powder, baking soda, salt, cinnamon, and nutmeg.
In another bowl, beat together the sugar, oil, eggs, and vanilla until well combined.
Gradually add the dry ingredients to the wet ingredients, mixing just until combined.
Fold in the grated zucchini and chopped walnuts.
Pour the batter into the prepared loaf pan and smooth the top.
Bake for 60 minutes, or until a toothpick inserted into the center comes out clean.
Let the bread cool in the pan for 10 minutes, then transfer to a wire rack to cool completely.