It would be interesting to test IGF-1 levels within the bounds of the vegan diet - as some foods definately have more protein than others.
It's been done by both the CR group and the Ornish group and found the isolated proteins and concentrated proteins raised IGF, even in a non vegan CR group.
However, a vegan group, following a healthy diet without isolated or concentrated proteins, had very low IGF-1 levels
CR makes sense is more ways then one but it takes some time to study it and understand it. And, when you do, you will see why the 3000 calorie/day approach to raw food veganism, is missing the boat.