Alicia Vikander has a great natural figure, but she had to put on an astonishing 12 pounds of muscle to play Lara Croft in “The Tomb Raider”.

Taking on a job like Croft’s need a little more meat than the average pirouette can supply.

Magnus Lygdback, her trainer, has worked with a number of powerful ladies, including Gal Gadot and Katy Perry. He spilled the beans on how Alicia got her incredible physique for the job of a lifetime.

“We covered it all,” Magnus said, “everything from classic lifting and strength training to more functional stuff. I like to switch it up, so we did everything from squatting heavy and doing deadlifts to pull-ups, push-ups, training with machines, training with bodyweight, plyometrics, explosive training.”

For over seven months, they worked together five to seven days a week, but they would never work together for more than an hour at a time. Magnus remarked, “What doesn’t happen in the first hour won’t happen in the second hour.”

They also included MMA HIIT, or Mixed Martial Arts High Intensity Interval Training, which is exactly what it sounds like.

Alicia  wasn’t supposed to build up visible muscles.

And what about that eight-pack? Probably the most difficult thing for anyone to accomplish. Magnus knows exactly how to make each of those abs pop out like Christmas lights.

Magnus explained, “I have a specific way of working the core.  I divide the core into three different days, and I approach the core differently every day.”

Planks and leg lifts are the focus of the first ab day, which focuses on “dynamic, static, or isometric abs,” Magnus follows up with “one day with rotational stuff, working the obliques,” similar to the wood-chop workout. Magnus then spends one day doing straight-up abdominis strength workouts, which are most likely weighted exercises to bulk up the core muscles.

Those core workouts were paired with techniques that worked her entire body. Alicia practiced heavy lifting five to six days a week, climbing two to three times a week, and boxing and MMA four times a week in the early months of training, according to Self. She also practiced stunts.

Alicia’s diet was the final piece of the Lara Croft jigsaw. Two months before filming began, she and Magnus decided to try the keto diet. “Since we were traveling so much over the holidays, we decided the keto diet would be best because it’s easier to control the macros that way,” he told POPSUGAR. “It was a high-fat, no-carb diet — not even low-carb. It’s always tricky the first couple of days, but [Alicia’s] willpower is just unbelievable, and she didn’t complain, even though I could see she was struggling a little bit. She kept on bringing it every day.”