According to the verified Twitter account of Dane Cook, he has slimmed down or bulked up for either Captain America, or most likely a part in the film. Knowing hi he could be joking, but you never
"Im minus 7% body fat now, bones replaced w/lightweight scandium alloy! Had 2 get shredded 4 Captain America audition & standup tour."
about 3 hours ago
Update:
Not knowing if he was joking or not, I asked Dane if he really was auditoning for the role, and he replied via Twitter:
"@Marvel_Freshman r u really auditioning 4 Captain America? Dc: I did already. They might b goin young. I say go RDJr route-gimme the part!
about 2 hours ago
So this could confirm that he was going in for the part of Steve Rogers, and that Marvel could have passed on him for the role.
MarvelFreshman: I...don't...know, I say if I think John Krasinski could be good, why not Dane. I can see him making the role his own, though unlike Krasinski, I have a hard time picturing him being serious. Anyhow He most likely could be talking about apart in the supporting cast. What do you think?