I'll give my input since I have taken this on and off. About a year or so ago, my boyfriend started taking this. He gave me one to try without working out and I HATED the way it made me feel. I got SO hot and almost felt like I was going to jump out of my body. I legit felt like I needed to run miles to get my energy out. Cut to a couple months later and I was going to the gym all the time (had nothing else to do since the boyfriend was in the Army and I was alone all the time). I switched the way I took it though. I only took it a half hour before working out. So as I was leaving work at night, I would take it so by the time I made it to the gym it would kick in. Taking it then had different results then the time I took it with my boyfriend. I had SO much energy but not enough to feel like "out of skin" feeling I had before. I sweated and definitely felt "hotter" but nothing I couldn't handle. When I took it that time, without even realizing I lost about 20 pounds. I felt amazing all the time and was never "tired" but when I got home from the gym, I was able to shower and go to sleep without any issues. I recently started taking it again but am down to only 1 pill left so I will be definitely going to GNC and buying another supply of it. I've read reviews on almost every "thermogenic" I've wanted to take and the Oxy has more positive than any other ones I've read up on and what's great is it works for both males and females so technically you can split a bottle with a significant other and save some money.