In an interview with ComicBook.com, Endgame VFX Supervisor Russell Earl and Industrial Light and Magic modelling supervisor Bruce Holcomb discuss their efforts in transforming the sexy washboard ab-ed Chris Hemsworth into an overweight videogamer. When asked if it was prosthetics or digital, the crew had this to say:

Holcomb: Under the arms. Earl: Under the arms, yeah. I think we ended up adding a little bit of hair here and there. I know, it was a great prosthetic, it just required some cleaning up. I think we added some jiggle in a couple of spots too. Earl also discussed how they managed to find the right balance between brawny Hulk and brainy Bruce Banner in the Professor Hulk character. Avengers: Endgame is currently the second highest grossing film of all time, only a couple of hundred million short of Avatar‘s $US 2.7 billion total. The fun part about this guy was it was taking down big muscley Smash Hulk and giving him a little bit more Ruffalo. We looked at all the previous models, and we did comparisons. We were looking at Ruffalo and the key art that we got from the guys at Marvel, and then it was really just taking all of those things and trying to dial in just the right amount of Hulk, keeping the big muscley dude, but then also getting enough of the smarts, or the brains, from Ruffalo in there.” (Source: ComicBook.com)

Endgame VFX Supervisors Discuss Professor Hulk and Fat Thor - 16