I definately felt sides when taking it empty stomach. I CANNOT take it without some food in me. I could never take it pre-AM cardio. I always did cardio empty stomach, then took T-Rex after breakfast. It just worked for me that way.
I never got jitters either. If I did cardio in the afternoon, I noticed I got hot faster and sweat more.
I'd stick with one a day for awhile. You will notice that you will get used to this dose after a week or so. Probably first thing you'll notice is your appetite comes back. Then you can go to 2 a day, spread out. I wouldn;t take 2 at a time for awhile - that nausea will kick your booty if you aren't ready for it,
Personal Info here - one big thing you'll notice with T-Rex is an increase in going poopy.
You'll likely have to go more often or they will be "more productive". This is a good sign, means your metabolism is chugging along faster.