The extremely unhealthy way Jared Leto gained weight for Chapter 27

Actor Jared Leto seems to have a penchant for physically (and psychologically) demanding roles throughout his nearly three-decades-long career. His first real challenged playing a young heroin addict in 2000's Requiem for a Dream. Leto lost 25 pounds, seemingly overnight, and befriended real-life addicts hanging out on the streets of New York City.

He later admitted that he hardly ate in preparation for the role, and he struggled to eat again after the film wrapped. He also experienced serious health complications, such as liver damage and bone marrow loss. As Elle relates, he started fainting on set.

"I was miserable. It was a painful, dark place, but it was rewarding," Elle reports Leto telling The Independent. "I don't know if you've ever fasted, but there were a couple of moments towards the end where I had hallucinations. I'd look up at the sky, and I'd get a feeling of complete serenity."

The role literally put him in a wheelchair

Leto's later film, 2007's Chapter 27, told the story of John Lennon's assassin, Mark Chapman. Leto's preparation for the role would lead him to alter his body in an even more dangerous way. Leto reportedly gained nearly 65 pounds to play Chapman. He packed on the pounds by eating pizza and burgers, and chugging pints of microwaved chocolate twice a day, as reported by Elle. The preparation process was indeed extreme, and led Leto to become confined to a wheelchair for a period of time — with the added weight, walking became painful, according to DigitalSpy.

Leto isn't unique; many actors will go to remarkable, even extreme, lengths to prepare for a role. Jared eventually regretted his decision to gain weight so quickly: "Really, it's a stupid thing to do," he later told The Guardian. "I got gout, and my cholesterol went up so fast in such a short time that my doctors wanted to put me on Lipitor, which is for much, much older people." All in all, he said, the experience was "a fascinating journey."