"The Big Sick" star stunned fans last month (December 2019) when he shared two shirtless photos on Instagram, showing off his full body transformation for his role as Kingo in the upcoming comic book adaptation.
The images went viral and in the accompanying caption, Nanjiani explained he'd spent the past year on an intense diet and fitness regimen to achieve his ripped physique.
His dedication to the job won him a flood of compliments from fans and celebrity friends, but there was one person in particular Nanjiani was especially proud to have impressed - former wrestler-turned-actor Johnson.
"Dwayne 'The Rock' Johnson said, 'Dense muscle is hard to achieve, my brother.' He thinks my muscle is dense!" the thrilled 41-year-old exclaimed on U.S. talk show "Jimmy Kimmel Live!".
"How he could see that? If The Rock says it, who knows better?"
However, Nanjiani admits having the pictures "explode" online was "super weird": "It was a weird couple of days... It really got out of control," he said.
Even his family members were blown away by his new muscular body, which caused a sensation in the star's native Pakistan.
"My brother said, 'Dad already sent your (half) naked pics to both families' Whatsapp groups,'" he recalled. "And then it goes in newspapers in Pakistan. So, I had all my aunts texting me pictures of myself, like, 'So proud of you.' It's weird to have your aunts sending you naked pictures of yourself."
Nanjiani confessed he wanted to share the photos as proof of his hard work paying off, because he wasn't sure he would be able to keep up his strict diet over the holidays.
"Who knows what I'm going to look like after Christmas?" he shared of his thoughts at the time, joking, "As soon as I saw the picture, I was like, 'The world must see this!'"
And after Nanjiani told presenter Jimmy Kimmel about all the foods he'd sacrificed to achieve his new body, he was surprised with a host of treats, including a box of pizza.
"I'm literally going to cry right now. I'm not joking. I'm shaking," he said as he began indulging. "Pizza's really good."