First thing one of those nerds will tell you is that it is not a stimulant. I've used it and love it. I can't use it for extended periods though because after a while it seems to cause weird side effects. After taking it continuously for several days I start to just not feel right in the head. I was even walking home from the gym one day after taking 2 caps pre-workout and was seeing shadows. There was a truck parked on the side of the road and I had to do a double take because I thought I saw someone inside, but this was not the case. Just didn't feel right emotionally. A bit depressed. At that point I'd stop for a week. It must build up in your system or something. First few days I felt amazing. Great energy and focus in the gym, don't need a pre-workout either. The stuff definitely works better with a big meal.