In a bowl, mix together the flour, baking powder, baking soda, salt and nutmeg.
In a separate bowl, beat together the egg, milk, oil and lemon juice. Pour into the dry ingredients. Add in the lemon zest and grated zucchini. Stir well with a fork until everything is moist and you have a very thick batter.
Pour the mixture into the loaf pan and smooth the top. Bake for 60 to 70 minutes until a toothpick inserted on the center comes out clean.