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

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

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

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 over meatloaf and continue baking until bubbling, about 5 minutes more.