1. Preheat oven to 375°F.
2. Melt margarine in a saucepan, then add the orange zest, and remove from heat.
3. Combine diced orange, rice, vanilla extract, and margarine mixture in a large bowl.
4. Beat eggs and sweetener together in another bowl.
5. Carefully fold the egg mixture into the large bowl.
6. Then, quickly mix everything together and pour it into a non-stick loaf pan.
7. Bake for 30 to 40 minutes.
8. Once baked, remove it from the oven, let it cool for 5 minutes, then serve and enjoy!