Place oven rack in lowest position. Heat oven to 350F. Grease bottoms only of 2 loaf pans, 8 1/2x4 1/2x2 1/2 inches or 1 loaf pan, 9x5x3 inches. Mix sugar and margarine with spoon in large bowl. Stir in egg whites until well blended. Add bananas, yogurt and vanilla. Beat until smooth. Stir in remaining ingredients except pecans just until moistened. Stir in pecans. Pour into pans.
Bake 8-inch loaves about 1 hour, 9-inch loaf about 1 1/4 hours or until toothpick inserted in center comes out clean. Cool 5 minutes. Loosen sides of loaves from pans; remove from pans. Cool completely before slicing.
Makes 2 loaves.
High Altitude (3500-6500 ft): Heat oven to 375F. Decrease sugar to 1 cup and baking soda to 1 teaspoon. Increase egg whites to 4. Bake 8-inch loaves about 45 minutes, 9-inch loaf 55 to 60 minutes.
Per serving: 152 Calories (kcal); 5g Total Fat; (26% calories from fat); 3g Protein; 26g Carbohydrate; trace Cholesterol; 189mg Sodium
Food Exchanges: 1 Grain (Starch); 0 Lean Meat; 0 Vegetable; 0 Fruit; 1 Fat; 1/2 Other Carbohydrates