Oh gosh, I didn't think about that. I mean, it's obvious (lighter person, less tolerance), but...
For me, my alcohol tolerance has always been at about zero. When I first started drinking, I'd have half a beer and feel it. At my heaviest weight of 207 I could have a whole beer and feel a little bit of a buzz coming on (pathetic, but true).
No matter my weight, my friend (who is a good 55 lbs lighter than me even after I lost 30 lbs) can drink me under the table (not hard). She's so petite! Even when I was 207 and she was 112, I was out after 2 rum and cokes and she went on to 4 and was kinda buzzed! Never lived that down...
Recently (after losing about 20 lbs) I had one mixed drink and a beer with a friend and I pretty much passed out. Did NOT expect that at all.
If my alcohol tolerance decreases significantly, I'll be out after one serving of anything. -sigh- I already get a hard time for it.
Although it does mean I have to spend less to feel buzzed.