I took Zyban almost three years ago to help quit smoking. I had attempted quitting many times but with the Zyban I was finally able to do it after 32 years of addiction. I did not use the patch with it but did chew an occasional piece of nicotine gum. Very occasional. And, knowing how I was about my smoking, I took the Zyban for six months so that I would not have a relapse. I can't begin to tell you how wonderful it is to be rid of that addiction!
I did not try to diet while quitting (only one habit at a time) and I did gain weight but probably not as much as I would have gained without the Zyban. The woman mentioned above who lost 20 pounds was probably already thin.
Quitting smoking does slow down your metabolism but I wonder if the low carb diet might actually help you during this time. The diet makes you feel better, more energy, and then you don't have those viscious circle carb cravings. Also, I drank lots of water during quitting and that is good for this diet too.
Zyban helps but it is still not easy. If you find quitting smoking and dieting at the same time just too much, I would recommend that you quit smoking first and then come back to the diet later.
Quitting smoking is the most important thing you will ever do for yourself and for all the people who love you and need you. If you fall off the wagon, get up, and start over. Take one day at a time and, sometimes, one minute at a time.
You can do this!!