Mark Ruffalo Did '500 Pushups a Day' to Prepare for This Role!

Mark Ruffalo went all out while preparing to play the Birdsey twins in HBO’s limited series I Know This Much Is True!

In a new interview, writer and director Derek Cianfrance revealed that the 52-year-old actor went through a lot of physical changes to play Dominic and Thomas Birdsey in the show.

While playing Dominic, Mark had to do about “500 pushups a day” and went on a 1,000 calorie-a-day diet to lose 20 pounds.

“I guess you could say he was always a little bit hangry,” Derek shared with The Wrap. “He was eating an egg white for breakfast and just starving. And he couldn’t eat for another 3 hours, and all he could eat then was a granola bar that had 120 calories or something, because he was on this strict diet. It created this guy Dominick who was just wiry and aggressive.”

Before they started shooting I Know This Much Is True, Derek and Mark had a meeting where Derek said Mark would first do 17 weeks of shooting all of Dominic first — then he would gain back 30 pounds to play his twin brother, Thomas, who struggles with mental illness in the form of schizophrenia.

“My very first meeting with Mark, I told him that if we were going do something like this, I couldn’t imagine us shooting in the morning, breaking for lunch and having him putting on a wig or a fake goatee and playing the second half,” Derek shared. “So we shot for 17 weeks and I would have Mark do push-ups — he was doing probably 500 pushups a day. All the time between takes, it was always our way to get Mark into the zone as Dominic.”

All episodes of I Know This Much is True are available for streaming on HBO Go and HBO Max now.