White poataoes act just like white sugar in your blood. They cause a rapid blood sugar spike - so much that some diabetes orgs will caution diabetics against eating them because it will cause such a strong insulin reaction.
If you eat them with some fat and protein it will slow the uptake of the sugar somewhat, so it is not as severe, but that is why they are on the less desirable list.
Sweet potatoes and yams are a more slow burning carb.
-------------- If you fall down seven times, get up eight.