Add the pieces of bread and crumbled crackers to the milk and egg white mixture. Let the mixture soak for a few minutes.
Add the lean ground beef to the milk, egg whites, pieces of bread, and crumbled crackers. Mix together.
Dice the onion. Add the diced onions to the lean ground beef mixture. Mix together thoroughly.
Add the Worcestershire sauce, onion powder, garlic powder, ground mustard, rubbed sage, and black pepper to the lean ground beef mixture. Mix together.
Coat a loaf pan with non-stick cooking spray. Spread the lean ground beef mixture evenly into the loaf pan. Put the loaf pan in the preheated oven at 350 degrees Fahrenheit for 35 minutes.
Mix the ketchup and brown sugar in a small bowl.
After the meatloaf is done baking for 35 minutes, use heat-resistant oven mitts to remove the meatloaf from the oven. Spread the ketchup and brown sugar mixture on the top of the meatloaf.
Put the meatloaf back into the oven for another 20 minutes.