I think this article is complete bull. As a smoker and someone who successfully quit on Zyban for 6 months, I know I gained weight and had more of an appetite after I quit smoking. After lapsing, my appetite significantly decreased going back to smoking. A perfect example is having a cigarette after dinner and having a much less desire for dessert afterwards.
I can only say that smoking decreases your appetite.. I would imagine that smoking less would decrease your desire for food and therefore modify your body's ability to gain weight. Can someone confirm this?