Jacked UP!

SWEATING IT OUT! THESE STARS PUT THE WORK IN TO GET RIPPED FOR THEIR ROLES - AND THEY'VE GOT THE SIX-PACKS TO PROVE IT!

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KUMAIL NANJIANI

The Eternals star wanted to look the part to play Marvel's first South Asian superhero, so he enlisted trainers, nutritionists and even a cardiologist and hit the gym every day.

But the transformation from hot nerd to hunk tapped into the 45-year-old's insecurity about his body. "I know exactly what I weigh every day," he admitted in one interview.

"And if I could change something, I would love not to think about that."

ZAC EFRON