HEAT oven to 350°F.
COOK onions, carrots and garlic in 1/4 cup dressing in skillet on medium heat 5 min. Transfer to large bowl; stir in stuffing mix and water. Add meat and egg whites; mix just until blended.
SHAPE into 9x5-inch loaf; place on rack of broiler pan. Combine remaining dressing and ketchup; spread over meatloaf.
BAKE 50 min. or until done (160°F). Let stand 5 min. before serving.