Well, similar stimulant effects (insomnia, trembling, anxiety, palpitations/irregular heart beat, and urinary frequency) could exist that are cross-referenced to caffeinated agents, however - we still must keep in mind the concentration of caffeine in guarana is somewhat lower and those that assume guarana = caffeine are in a land of confusion (hmmmm, without Genesis being cued in the background - though many not get this reference).
You know, that Fatty Acid Rountable discussion with Dr.D from AX actually was heavily touted at bb.com in its aftermath and there was a LOT of questions regarding this. To follow was a sequence between myself and another poster based on a guarana question you may find of interest.
The question:
http://forum.bodybuilding.com/showpo...1&postcount=25
My response:
http://forum.bodybuilding.com/showpo...1&postcount=26
Something too to watch for (but more often in teas and such with guarana but are still of unknown concern) is the high tannin content which contributes to astringent activity as I mention in that piece above. It will do one of two things, tighten the bowel -or- loosen it. Tannins happen to be a component of one popular supplement on the market these days and this could account for many of the weight loss effects, if any are to be had.
Overall, it seems as though you are handling it well. You can continue on and if it ends up making you feel bad, then stopping use would obviously make sense. That said, keep in mind that the effects also will have a significant wean-off time frame and the potential for withdrawl symptoms (similar to caffeine).
D_