From the Gym responsible:
http://www.gymjones.com/knowledge.php?id=36
There is no way to definitively know whether or not they were on roids; thus I dont understand why somone would state it as a fact... possible; oh [censored] yeah... fact; no.
There is no way to really know the exact extent of cgi work, etc. I dunno about you but I know no one in that computer editing room.
Hollywood actors in recent years have been showcasing purely visual transitions that are often pretty nuts generally on a short time frame. With millions of dollars in motivation and dedicated staff avaliable in the form of nutritionists and trainers I can imagine a LOT happening in a short time. I also have no doubt that many time steroids are sought after and/or used. I also have no proof as to when those times are.
They still dont drug test everyone in baseball.... and hollywood is less regulated than that.
As such I hardly think results should be called impossible. We can conclude that we simply don't and won't know all the facts. And that training in any manner specifically mentioned in articles about various movies is generally not the best suggestion nor will it assure one of ever looking the part.