Robert Pattinson counted sips of water before filming The Batman's shirtless scenes

Robert Pattinson spent the days leading up to his shirtless scenes in The Batman "counting sips of water".

The British actor told People that he had to be careful about every single thing he consumed in the days leading up to Bruce Wayne's topless scenes.

"You just cut down and cut down and cut down before the couple of scenes with your shirt off, and you're counting sips of water," he said.

To prepare his body for the Batman role, he explained, "I had about three months before the movie started, and then you're working out before and after work all the time."

When asked whether going shirtless motivated him to cut down, Pattinson admitted, "Shame is my biggest motivator, 100%."

The 35-year-old explained that he felt ridiculous rehearsing the character at home in his normal clothes but found more confidence as soon as he put on the Batsuit.

"The closer I got to the shoot I got more and more paranoid - you know, it feels ridiculous when you're just sitting at home in a T-shirt - and then you put it on... It's got an elemental power to it," he shared. "People react to you differently, the crew reacts differently. Your entire world suddenly changes.

"And then you kind of catch this glimpse in like, the subtle reflection or a shadow on the floor and you realise that the character's just way bigger than you... It's kind of like wearing a crown or something."

The Batman is in theatres now.