Well, I probably am the most common person, like smoking no stop, or probably eating everything I can, since I'm never getting fat as you already know -_____-
I used to smoke as well, then I decided not to be nervous anymore. But seriously smoking is surely one of the worst things you can do your body. I've been smoking for years but stopped over a year ago (wasn't hard) and now I feel much healthier. Putting nails in your own coffin is certainly the worst way to deal with tense situations. I can only suggest you to find a suitable distraction (e.g. playing games, reading).
I'm not a big smoker, like 20+ at day, probably just 5 or 6, they help me think mostly. I'm not even dependent of it, the problem is just when I'm stressed -_____-
I used to smoke but since getting on ecigs, I've stopped with the stinkies. Just the nicotine you need to kill the desire/crave. Now when I take a cigarette, I regret badly. The smell, the feeling etc. Because now I can see I can get the same nicotine without those bad effects and without going out or stinking the room.
Eating a lot has it's disadvantages. I'd recommend eating a few things (how much depends on what kind of food) that you like the most.