Hi there!
I just wanted to put my "two cents" regarding thermogenics. I recently trained for a bodybuilding competition (about a year ago) and have battled diets and my weight for 6 years now. I have tried every thermogenic out there. Most recently, Hydroxycut.
My advice it to make sure you are taking a safe amount and don't let it become something you rely on. My problem was when I first began taking it, the ephedrine in the pills curbed my appetite so much, that I'd barely eat. Shortly after taking the pill, I also experience jitters, dizziness, and extreme highs and lows when it came to energy. Those side effects all seemed to go away when my body became used to ephedrine. The thing I would caution is that when your body does adapt to it, don't get in the habit of taking more pills to feel those "side effects." Just because the side effects go away, doesn't mean the pill isn't working. That's when people over dose on ephedrine, and we've all read the horror stories.
I was also a trainer and the gym I was at was forced to pull products containing "ephedrine" because of their serious potential. The company quickly turned around and put the product back on the market, just under a different name. Ephedrine has many different names, so be watchful for those.
I wouldn't discourage anyone from taking thermogenics, I would just suggest that you make wise and educated choices. I recently had to get myself off of them because I was becoming dependent on them and that's not okay. Use them for a few weeks, then give your body a break for a week or so. Or try 2 days on, one day off.
Hope some of you can find this info useful
Good Luck!