I just went off of the phentermine/B-12 injections and I lost 35 lbs in 3.5 months. I got the B-12 injections once per month from Dr. Mini Thakkar in Barrington. I have been off of the pills now for about a month and have gained 3 lbs. back, but I am not starving. I just slacked more than I should have over the Holiday weekend last weekend. The phentermine pills definitely help to curb your appetite. The B-12 shots were supposed to increase your energy, but I found I was more tired after my monthly shot- for about a week. The key to this combo for weight loss is the exercising- the pills do not make you loose weight. You need to make exercise part of your everyday life, and you need to change your eating habits. I found it easy to do while on the pills, and now I am determined to maintain this new eating/exercising lifestyle. It is a pricey endeavor, but it worked great for me. The phentermine started giving me side effects, so I went off of it. I only had 5 more lbs. to loose. I had the common side effects the first week, but then they went away. Then, around 3.5 months, I started loosing a ton of hair, and was really irritable and cranky. So, I stopped- much to my doctor's dismay. Read the forums on phentermine.com for more info.- just remember that different people react differently to the stuff. Good luck!