Sweet potatoes are the edible, underground root of the sweet potato vine, with a tan-colored skin and sweet-tasting, bright orange flesh. Baking is a popular method of preparing them. Low in fat, a baked sweet potato is a healthy source of calories and nutrients. One medium-sized, baked sweet potato is approximately 2 inches in diameter and 5 inches long. It weighs 114 grams and provides a total of 103 calories. That same medium baked potato has approximately 24 grams of carbohydrates with 3.8 grams of fiber and 7.39 grams of sugar.