Preheat your oven to 350°F (175°C). Grease a loaf pan.
In a mixing bowl, combine flour, baking powder, baking soda, cinnamon, and salt.
In another bowl, whisk together vegetable oil, granulated sugar, brown sugar, and eggs until well combined.
Gradually add the dry ingredients to the wet ingredients, mixing until just combined.
Fold in the grated carrots 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.
Allow the loaf to cool in the pan for 10 minutes, then transfer to a wire rack to cool completely.