Metabolism and Smoking

I have heard that quitting smoking slows down your metabolism. Can anyone tell me if there is any truth to this? I only ask because I just started back on MFP on Jan 2nd, and was losing around 3lbs a week. I stopped smoking almost 2 weeks ago, and haven't moved an ounce on the scale in the past week and a half. I know, there are many different things that could contribute to why, but I really am just interested to find out of my metabolism is slowing. Not that it matters...I rather enjoy being able to make it through my workouts without having to use my inhaler...but curious nonetheless..