Can smoking cigarettes affect weight gain? i smoke about 1 pack every two days.

No: I presume you are asking if smoking can prevent weight gain. Avoiding weight gain is used by many people as a justification for smoking. But you have to gain 100 pounds to have the same risks as smoking two packs a day. While you smoke less than this, there is no question that smoking is way worse for you than gaining even a few pounds. Please focus on quitting tobacco!