Preheat the oven to 350°F (175°C). Lightly spray a 9 x 5-inch loaf pan with cooking spray, then dust with flour and set aside.
Lightly spoon 1 cup all-purpose flour and 1 cup whole wheat flour into dry measuring cups, level each with a knife, and add both to a large bowl.
Add 3/4 teaspoon baking soda and 1/2 teaspoon salt to the flours and whisk to combine.
In a separate mixing bowl, place 1 cup sugar and 1/4 cup coconut oil. Beat at medium speed with a mixer until well blended.
Add 2 large eggs to the sugar mixture one at a time, beating well after each addition.
Peel and mash 3 medium bananas with the back of a fork. Add the mashed banana, 1/4 cup yogurt (plain, low-fat), 1 tablespoon lime juice, and 1/2 teaspoon vanilla extract to the mixing bowl and beat until combined.
Add the flour mixture to the mixing bowl and beat at low speed just until the batter is moistened. Do not overmix.
Fold 1/2 cup coconut flakes into the batter using a spatula.
Spoon the batter into the prepared loaf pan and smooth the top. Sprinkle the remaining 1/4 cup coconut flakes evenly over the top and gently press them into the batter with the back of a spoon (do not mix them in).
Bake for 45 to 60 minutes, checking at 45 minutes. The bread is done when a toothpick inserted into the center comes out clean or with a few moist crumbs.
Remove the loaf from the oven and let it cool in the pan for 10 minutes. Then transfer the loaf to a wire rack to finish cooling before slicing.