My mom did that when I was a kid. It didn't work -- she coughed her way through a pack or two and then remembered that she liked being alive...
Plus, when you smoke you always smell bad. Sorry to offend any smokers, but the smell of smoke is seriously overpowering. So if the plan worked, you'd be skinny and stinky and have charred lungs. Sexy...
I know it sounds like I'm making light of it, but really...you already know it's not good to replace overeating with smoking because you're trading bad health for bad or maybe worse health.