Heat the oven to 375°F. Lightly coat a small baking dish with the olive oil.
Put the sweet potato chunks in a saucepan and cover them with water. Bring to a boil, then cook until fork-tender, about 12 to 15 minutes. Drain well and mash until smooth. Let the mash cool slightly.
In a large bowl, combine the ground turkey, grated carrot, grated onion, egg, breadcrumbs, chopped sage, salt, pepper, and mashed sweet potato. Mix gently just until evenly combined.
Shape the mixture into a loaf in the prepared baking dish. Bake until the center reaches 165°F on an instant-read thermometer, about 45 to 55 minutes.
Let the meatloaf rest for 10 minutes before slicing and serving.