Preheat the oven to 350°F (175°C). Grease and flour a 9×5-inch loaf pan.
In a medium bowl, whisk together the flour, baking soda, baking powder, salt, cinnamon, and nutmeg.
In a large bowl, beat the granulated sugar, brown sugar, and eggs until smooth and creamy.
Add the vegetable oil, buttermilk, and vanilla extract to the sugar and egg mixture and mix until combined.
Gradually add the dry ingredients to the wet ingredients, stirring just until combined.
Fold in the grated zucchini until evenly distributed.
Pour the batter into the prepared loaf pan and smooth the top.
Bake for 50 to 55 minutes, or until a toothpick inserted into the center comes out clean.
Remove the bread from the oven and let it cool in the pan for 10 minutes.
Transfer the bread to a wire rack to cool completely before slicing.