Step 1

Preheat oven to 400 degrees F (200 degrees C). Spray a 9x5-inch loaf pan with cooking spray.

Step 2

Heat olive oil in a skillet over medium heat; cook and stir green bell pepper and onion in the hot oil until onion is transparent and bell pepper is softened, 5 to 10 minutes. Add garlic and cook until fragrant, 1 to 2 minutes.

Step 3

Combine ground beef, bread crumbs, eggs, carrot, zucchini, salt, pepper, and bell pepper mixture in a large bowl; mix well using your hands. Press meat mixture into the prepared loaf pan.

Step 4

Bake in the preheated oven until no longer pink in the center, 35 to 40 minutes. An instant-read thermometer inserted into the center should read at least 160 degrees F (70 degrees C). Spread ketchup on the top of the meatloaf and continue baking until bubbling, about 5 minutes more.