Individual food choice will not dictate a higher rate of fat that you put on only the excess of calories will.
The GI is irrelevant to healthy active people here is a good study on GI
alanaragon.com/elements-challenging-the-validity-of-the-glycemic-index.html
Hope im aloud to post links if not please some one let me know and I will delete it.
In short if you like white potatos eat them or any carb source you prefer