In reply to r fizzle:
I tried using a recovery drink (which is 4:1 carbs to protein by energy) for a while when I was doing lots of indoor climbing. It only served to keep me from losing weight, as I'd got my calorie calculations wrong. Protein drinks are really geared up for helping to build muscle. Now, if you don't have enough muscle, they may be beneficial. This is unlikely (but not impossible) for a climber. (I've noticed that, although the local wall-wads tend to be built like tent poles, the super-stars are often considerably more muscly. Food for thought...)
I've recently started going to the gym instead of some climbing and that's made more of a difference to my strength. Obviously you need to work out what's best for you, but I'd recommend trying to work out what's holding you back, and address that. If it's *really* strength, then perhaps some gym time and thoughtful diet control are what you need.
I began going to the gym for a couple of reasons. One, I wanted to lose weight, and I wanted to do something that would burn more calories than climbing. Two, I thought that I could benefit from more overall fitness. I'm doing a programme at this gym which is very general - not sport specific at all. I've found that more core strength, and a better awareness of which muscles are doing what has helped me in my climbing.
So try different things. Observe what happens, and if they don't work, change them.