Which actors have pushed the boundaries to the limits in a role

How about Christian Bale in The Machinist. That’s serious commitment.

It's an obvious one but de niro in Raging Bull. He went from peak physical fitness to fat bloater in one film. Apparently they stopped production halfway through so he could fly to Italy for a few weeks to fatten himself up on pizza and ice-cream. Now that's my kind of method acting!

If you're including pushing the boundaries of taste and acceptable screen mores, the first I can clearly remember is Brando's role in Last Tango in Paris, which bordered on porn. It was rated X at the time. Now has a NC-17 rating.

same is true for tom hanks during castaway but that's a luxury they have. I am not that impressed with their "commitment" when they can take 8-9 months to gain weight.

Bale only had 6 months, from Machinist to Batman Begins. Gaining weight in 8-9 months is fine. Just pizza, Whataburger and Beer would do it. But beefing up the right way takes a lot of effort. Yeah you can say they don't have a 9-5 job, kids to take care of, household chores, so they can do it.

__________________
My Favorite Films

First one who springs to mind is Leo DiCaprio in The Revenant. Dude suffered through freezing temperatures, slept in an animal carcass and ate raw bison. That's commitment.

Lon Chaney was well know for creating his own make up for horror roles often to uncomfortable circumstances. In Phantom of the Opera (1925) to transform his nose, Chaney applied putty to sharpen its angle and inserted two loops of wire into his nostrils. Guide-wires hidden under the putty pulled his nostrils upward.

Christian Bale was the first actor that popped into my head when I saw the title of this thread.

A similar thing happened with Tom Hanks in Cast Away...Robert Zemeckis shut down production for a couple of months so that Hanks could lose 30 pounds before resuming the rest of filming.

I also read that Joaquin Phoenix dropped 52 pounds before starting Joker, but I don't know how long he had to do it.

Initially my reaction when i heard this in 2015 was something along the lines of , he always had heaters available while making the movie and a trailer to go in whenever he wants after a cold take. Even sleeping in animal carcass is not really a stretch because it was done in original star wars movie. Eating bison liver and spitting it out is not really a health hazard. The problem is when you digest it.

But with all that being said, vast majority of the movie is him suffering. They had to do lot of takes of him emoting. Now that must be hard given the surroundings and the environment the movie is set in. Doing the same scene with no dialogues again and again in those conditions must be jarring. However i can't say how hard that is compared to reading and memorizing hundreds of pages of sorkin's tech dialogue in steve jobs.

Much raw bison liver eating experience have we?

Health risk or not, it was raw and inmediate. That's raw. bison. liver. On your tongue and full of bloody iron flavor.

I can't even think of cooked beef liver without being overwhelmed by gag reflexes. Or from just the smell of fried chicken liver. But sure, eating raw bison is something to scoff at.

I just remembered that Nick Nolte lived on the streets for six weeks before he began shooting Down and Out in Beverly Hills