Tiger lady Olivia Munn needed to undergo a celebrity weight loss diet in order to become Pyslocke for "X-Men: Apocalypse." The actress needed to lose 12 lbs and had to take Victoria's Secret Model Gisele Bundchen.

This celebrity weight loss was successful that she was able to fit into her Psylocke outfit. According to Perez Hilton, she didn't set out to lose weight. Instead, her diet was to gain strength. She was taking on tae kwon do traning and was on the 80-20 Gisele Bundchen diet. The majority of her food intake came from fruits and vegetables. The 35 year old told E Online that it was a byproduct of her goal to be healthy. "When I started on X-Men, I had been training and doing regular personal training and trying to eat in a healthy way," she said.

Celebrity weight losses are not a new thing. There are tons of actors out there who also needed to shed a few pounds for their roles.

Take for example, Chris Hemsworth when he had to look like he was starved to death and living in the middle of the ocean for "Heart of the Sea." Chris Pratt may have looked buff in "Guardians of the Galaxy" but before that he was a big mass of 70 lbs of fat. Matt Damon had to starve himself and ran 12 miles a day to become that heroine addict in "Courage Under Fire." Even Zoe Kravitz had to drop 90 lbs to play an anorexic woman in "The Road Within." Remember that time Matthew McConaughey lost 50 lbs to play an HIV patient in Dallas Buyers Club? Well, now he still hadn't gained those pounds back.

"X-Men: Apocalypse" is already in the theaters.