The quantity of protein in sweet potatoes varies depending on the cooking method. But in general, they are poor sources of protein.
1 large baked sweet potato weighing 180 g contains about 3.6 g of protein. Whereas, boiled sweet potato of the same size has about 2.5 g of protein.
The reason for this difference is when we boil this tuber the water content of it increases and hence the overall quantity of protein goes down.