Lightly coat an 8x4x2-inch loaf pan with cooking spray; set aside. In a medium bowl combine flour, baking powder, baking soda, cinnamon, and salt. Set aside.
In a large bowl stir together the egg whites, banana, sugar, and oil. Add flour mixture all at once to banana mixture. Stir just until moistened (the batter should be lumpy). Spoon batter into prepared pan.
Bake in a 350 degree F oven for 45 to 50 minutes or until a wooden toothpick inserted near the center comes out clean.
Cool in pan on a wire rack for 10 minutes. Remove from pan. Cool completely on rack. Wrap and store overnight before slicing. Makes 1 loaf (16 servings).