A friend of mine showed me an article recently debating the merits of soy protein isolate v. whey protein (they discuss both concentrate + isolate). Some of the discussion was a little over my head - particularly in passages relating to estrogen receptors - such that while it sounded good, I had no way of verifying its accuracy. And some of it clashed with what I thought I already knew, particularly: "For years, bodybuilding gurus have recommended the use of soy protein for pre-contest bodybuilders who need to shed body fat while keeping as much lean muscle as possible." (IK/other competitive BB'ers on here, is this true? I had always thought soy would cause perhaps more bloating than would be desired pre-comp.)

So I looked at a few more articles (knowing that I don't really know much about the sources, but nevertheless) and it seems to say simply that soy is nutritionally better than or equal to whey (certainly better according to the first article) but that whey is preferred for its fast absorption rate.

Primarily, I was curious if that was an accurate (if crude) summary of the distinction between the two, or if the case for soy is being overstated. Second - if it is true, and whey's most useful application is for quick absorption, would it be best to use soy as one's primary source of protein and only use whey for pre/post workout?

Thanks in advance for any replies!