I've been using Hot-Rox for last week and seems to really be helping. I was losing fat like crazy the first few weeks of my diet ( (and gaining muscle), but then my metabolism slowed to a crawl. I saw HOt-Rox at Wal-mart and decided to give it a try. It's given me a noticeable boost and a "heated" feeling. No rapid heart beat or jitters like ephedra. It comes in three different strengths. Of course the one I got at Wal-mart is the weakest and it is mislabeled with limit of 4 tablets a day, but I read on the biotest website that you can safely go up to 8 a day. They do recommend you start off with 1 tablet twice daily to assess your tolerance. Make sure you take it on an empty stomach and wait 45 minutes before eating.