Could you please clarify what you mean by "fruit sugar"?  I thought that
the sugar present in fruit was fructose.  If this is incorrect, and fruit
actually contains fructose, sucrose and glucose, then are there any food
source that solely contain fructose??  I am getting ready to experiment
with some of the suggestions in Cordain's book, but am aprehensive about
adding "unlimited" fruit after years of low-carbing.  The reason I want to
experiment is that I am hoping fruit could help with the constipation I
invariably experience when going ultra-low carb, and I also thought it
could replenish glycogen stores.  I simply tire out way too soon when
working out after weeks of ultra low-carbing.  I am thinking of only eating
fruit during a meal that also contains protein to blunt any insulin
spikes.  Thoughts??