Henry Cavill's 'Superman Workout'

INSIDE EDITION has learned the secrets behind Superman Henry Cavill's workout that transformed him into the Man of Steel.

He's the Man of Steel and he has the body to match. But just how did actor Henry Cavill get that Superman physique?

Mark Twight was Henry's trainer at Gym Jones in Salt Lake City, Utah. He's the same trainer who got Gerard Butler in shape for 300. He says he bulked up Henry's muscles by making him eat a staggering 5,000 calories a day!

"I'm thrilled with how he looked in the film," Twight said.

To get Superman's body, Henry had to avoid processed foods and eat mostly whole foods like:

Whole milk
(and) vegetables

And Henry's workout wasn't exactly for the faint of heart. Two grueling hours a day of a special kind of high intensity interval training called Tabata.

"Henry said one day, 'Look, I want to look the same out of the suit as in the suit so when we have to do the shirtless scenes everyone will know that it's not fake," Twight stated.  

In order to get those broad shoulders and narrow hips, Henry's form had to be perfect during the workouts. His workouts are being used to recruit for the National Guard.

Henry did thousands of squats and, instead of doing regular pull ups, he did chest pull-ups. That means you don't just touch your chin to the bar, you touch your chest to it.

Now that filming is over, Mark says Henry Cavill is still working out. Apparently, he doesn't want Superman to be seen on the beach this summer looking flabby.

"You can never show up anywhere, having played the Man of Steel, and be overweight," Twight said.