It is difficult to tell how much of my increase in climbing ability was due to weight loss and how much was due to increase in strength, because these kind of go hand in hand. When I train more, I lose weight and vice versa. However, physics bear out the fact that it takes more energy to push more mass up a hill.
It has been argued that Lance's climbing prowess can be attributed to the weight loss he had while recovering from his cancer treatment.
I do know that losing weight slowed down my descents. Galileo be darned.