In reply to mark s:
I'm utterly shocked that someone stated they were 45kg - hello?!! shouldn't you be dead?! if not, why aren't you climbing 8c?
There's no excuse for it. If you're super-light you can be piss-weak and still climb hard. Look at Dave Graham. He only needs a light wind to equal out gravity for him and he floats up stuff.
Then you've got all the European guys putting up 9a's and 9b+'s - they can't be much over 11stone when wet.
I think people like Chris Sharma, Klem Loskot, the Hubers etc are exceptions to the rule. Sharma's undeniably gifted, Loskot must be the strongest climber in the world and the Hubers, well a bit of both.
Imagine putting the muscles of a heavy but strong climber in someone who's 45kg - they'd pull the crag to the floor.
It's all about power to weight ratio, same as with cars, surely?
I'm 5'8", 14stone (196lbs, 89kg) and climb about F7a on a good day. Admittedly I am a fat bastard these days.
I was climbing 7a+, pushing 7b when I was at my lightest, which was about 12stone, so I'm not far off at over 2stone heavier (I'd say 75% flab, 25% muscle).
I think I could get back there without going under 13stone now as my muscles have had to get stronger to pull my weight up things. Even climbing a 6a takes an immense ammount of strength and energy!