Fassbender's role as sex addict Brandon in Shame required him to film full-frontal nudity, but the actor insisted to Reuters that the on-screen stripping was entirely appropriate for the character.
"I knew the sex wasn't there for titillation or exploitation. It was there as a way for the audience to access this guy's head," Fassbender explained. "I saw all the sexual encounters as being very revealing about what's actually going on inside Brandon."
Fassbender went on to predict that those who see Shame will consider Brandon's sexual conquests to be tragic, rather than titillating.
"I didn't want him to be in great shape. I wanted to keep that sense of an addict, so we never really see him eat, except Chinese while watching porn. He drinks Red Bull in the morning," the star said.
"Here's someone who just eats as fuel. There's not much pleasure there. A lot of the time I wanted to be repulsive in the sex scenes. I wanted to look ugly as opposed to looking good."
Fassbender previously revealed that he will take a break from acting after his next film Prometheus is released.
Shame is now playing in the US and opens on January 13, 2012 in the UK.
> Michael Fassbender considered for Darren Aronofsky's Noah
> Michael Fassbender: 'Prometheus is not an Alien prequel'
Watch a trailer for Shame below: