Sweet potatoes are considered a starchy vegetable, but they are also a great source of nutrition. Starchy vegetables are usually higher in calories than non-starchy vegetables which have higher water contents and fewer calories (cucumber, lettuce, peppers, etc.). That said, starchy vegetables provide great nutrition and fiber, are lower in calories than many other foods, and contain no fat (unless fat has been added during cooking.) Sweet potatoes are a good source of fiber and potassium. They are also an excellent source of vitamin A and vitamin C.