In a large bowl, whisk together sugar and eggs. Whisk in coconut oil, then once combined, stir in bananas, carrots and vanilla extract. Once mixed, add in half of the dry ingredients. Mix with a large spoon until incorporated, then add in the buttermilk. Add the remaining dry ingredients and stir until batter is somewhat smooth and not many lumps remain. Using a 1/4 cup measure or an ice cream scoop, fill lines 3/4 of the way full with batter. Bake for 18-20 minutes, or until cupcakes are set in the centers. Set aside to cool completely.