I have been on gabapentin for over 2 years now and I have gained some weight. I was told that since it makes you drowsy and tired (at least it does me) and that keeps a person from wanting to exercise which in turn slows down your metabolism, which in turn makes you gain weight. While I have gained about 5 lbs in 2 years, I know some would say that's not a lot, but I am only 5'2", so that is a lot. I know I have to continue walking and riding my bike, no matter what. I am still waiting to be diagnosed with fibro, although I was diagnosed with myofascial pain syndrone 2 yrs ago, hence the reason for gabapentin. Myofascial is pretty much the same as fibro, except pain in limited to certain areas of the body. For me, it was the right side from my shoulder down to my wrist, where I had carpal tunnel and tendonitis surgery which resulted in nerve pain. But now, my pain has spread throughout my body. I also hurt my back 8 mnths ago and the pain has never went away, even through therapy, decompression, massages, etc. While, I don't have all the tender trigger points that most have, I do have some. I have some of the other symptoms, though. I had my thyroid tested and it came back normal. I don't know what else I can be tested for to find answers. ?