When pictures of JK Simmons looking extremely hench hit the internet not long ago, many people assumed he'd got ripped for his part in the upcoming Justice League.

But he's now told Business Insider that he hasn't gained those rather impressive muscles to play Commissioner Gorden in the DC Comics movie.

In fact, he's actually that buff anyway as he pops to the gym regularly to stay healthy, and the casting and his hot body are "all coincidental".

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"Those were shot at the end of April. I'm huge now!" Simmons joked.

"After the second and final time that I got hugely fat in my life and when I lost that weight six or seven years ago, I pretty much decided that I was going to stay in decent shape for the rest of my life."

He first felt inspired to change his body shape when he was watching back episodes of Oz in 1997, where he played neo-Nazi Vern.

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"I was overweight and soft and here I am playing the head of the Aryan Brotherhood in this maximum-security prison in the first-ever HBO original drama," Simmons said.

"I was watching the first season when it came out and I just thought, 'Wow, I don't believe this guy at all. I have to get my ass to the gym and be a believable hardass.'"

Meanwhile, director Zack Snyder has admitted to tweaking the tone of Justice League after being caught off guard by the not-all-that-positive reviews of Batman v Superman.