Heat oven to 375°. Line a 9 x 5-inch loaf pan with foil and coat with nonstick cooking spray.
In a large bowl, combine ground beef, egg whites, bread crumbs, 1/2 cup of the tomato sauce, the zucchini, onion, sweet peppers, garlic, 3/4 tsp of the salt, the sage, oregano and 1/2 tsp black pepper. Spoon mixture into prepared loaf pan; press flat.
Bake at 375° for 30 minutes. Spoon remaining 1/2 cup tomato sauce over top and bake an additional 25 minutes. Cool 15 minutes before slicing into 6 servings.
Serve meatloaf with lentil mash and steamed broccoli.