I just read an article about Brandon Routh's training regiment and diet in preperation for Superman Returns, and all my question's about Routh's physique were answered in a couple of paragraphs, and I just want to add in before I get started that yes, he wears a muscle suit.
In the article, Routh says that while training for Superman Returns, he mostly stuck to circuit style weight lifting, which is for the most part machines, and ate alot of fruits and veggies for his diet. I was in f-ing amazement after reading this article. That is NOT how you bulk up for a superhero role in which your character you play is supposed to be a bulkier guy. I know Routh was doing what he was told, but damn, change up who your listening to. Even Tobey Maguire hit the heavy wieghts and drank six protein shakes a day along with pasta, cheese, and what not, and even then all he got was really cut, where as Superman should look like a big strong farm boy, ala Tom Welling.
Brandon, for the sequel, hit the big heavy weights an hour a day and scarf down all the food you want except fast food and pop. And then, about 4-6 weeks before filming, clamp down on the diet with more lean proteins and less carbs.