Read up on Resistant Starch; nutritionally potatoes can behave more like soluble fiber (eg: indigestible) than they do with wheat and sugar based carbs. Besides

Read up on Resistant Starch; nutritionally potatoes can behave more like soluble fiber (eg: indigestible) than they do with wheat and sugar based carbs. Besides not getting digested and turned into glucose, they're also very satiating. That makes it difficult to consume enough of them to exceed your caloric needs.