A good book I found on the subject at my local library is Bodystat : How to Reset Your Fat Thermostat Permanently :
http://www.allbookstores.com/book/0670859559There are many other books along similar lines on the same library shelf.
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The authors of this particular book outline several ways one can accomplish long term goals - some of it is "extreme" while other parts are just minor changes. I picked the minor changes route and lost 50 pounds of fat over the course of a year - I also took on a weight training program so I converted mass from fat to muscle, I lost only 40-45 pounds of weight - having gained 10 to 15 pounds of muscle in the process of losing fat.
After I stopped using speed I gained a lot of fat - Although while on speed I was thinner than a rail, after speed my eating went through the roof. Basically all sorts of drugs designed to reduce hunger will have the same effect once you stop.
Smoking is similar to using speed - it suppresses your hunger and once you stop taking the drug the hunger takes over. What one needs to do is find a way to feed the hunger with low calories so one can feed the need filling the stomach while eating less calories.
Taking a drug to offset the loss of another drug just will not work. Once you stop taking the next drug you will be in the same boat.
This book will also explain to you why starvation diets just do not work. The body is designed for survival - starvation is anti-survival and the body has many ways to survive - unfortunately in our modern world with an abundance of high calorie foods the survival modes end up costing us in the fat department. Using drugs to offset hunger sets you up for a starvation period, the body will respond to that and will ultimately seek to gain fat to offset the famine.