There is no question that when I am doing a flap of skin (tummy tuck, facelift, mastopexy or reduction of the breast), I require patients to stop smoking for three weeks before the procedure. The effects of smoking are almost gone in three weeks.
Smoking introduces carbon monoxide into your system, which steals oxygen from the tissues, as well as nicotine, which crimps down on the blood vessels. There are many side effects, including longer healing time, worsened scars and more complications in patients who smoke.
There are things that you can do to mitigate the effects of smoking, such as modify your SMAS facelift to pull more on the deep tissues and less on the skin, or take the tension off of the deep tissues of the abdominoplasty. But, we are trying to stack the deck in our favor, not in the favor of having more complications. I have for years put people on oxygen after a flap surgery just to increase the oxygen in the tissues for a few days.
Using patches or gum sounds good, but you still have the effects of the nicotine from these products. I remember a well-intentioned internist who tried to be very nice to my patient by ordering the patch after her tummy tuck, just to watch the lower area in the midline necrose a section of skin about the size of a baseball.
Complications that arise because of the choices that our patient makes is something that we would like to help avoid. Most board certified plastic surgeons and members of the American Society for Aesthetic Plastic Surgery who I know and respect really want their patients to have better outcomes, so they will require their patients to quit smoking for at least 3 weeks before the procedure in order to decrease the potential problems.
There are procedures that do not have flaps, such as liposuction, that I don't make as big a fuss over if patients smoke before surgery, even though they also have higher complication rates (like pneumonia after anesthesia, or spontaneous pnemothorax - dropped lung). There are no studies showing more capsular contractures with breast augmentation in those who smoke, but in my practice, I have noticed that patients who smoke seem to be more likely to end up with hard breasts after augmentation.
So the short answer is that you will get better healing and fewer complications if you maximize the oxygen going to your tissues by not smoking. Conversely, if you smoke and thus deprive your tissues of oxygen, you are at greater risk for more complications and worsened scarring.
