Charlize Theron has been known to dramatically transform her figure for movie roles — like when she gained 30 lbs. to play murderer Aileen Wuornos in 2003’s Monster and earned her first Oscar in the process. But the actress is also honest about the hard work and less-than-glamorous aspects of gaining and losing weight for a role.
For her new movie Tully, out May 4, Theron transformed herself again and gained almost 50 lbs. to play a mom of three with postpartum depression. The South African-born star tells PEOPLE in the latest issue that losing the weight at age 42 was much more difficult than when she had to do it the last time, at 27.
“My body flipped me off quite a bit. It’s just way different when you’re older,” she admits. “Also this time around I dealt with depression for the first time in my life. I just didn’t eat very healthy and a lot of the processed sugars and things just really put me into a terrible depression, and I’d never dealt with anything like that in my life. It totally took me off guard.”
For much more on Charlize Theron and her new movie Tully, pick up the latest issue of PEOPLE, on newsstands Friday.
Theron adds: “I was very heavy, literally and figuratively. My soul just felt really heavy on this film, and I was just really unhealthy and I threw my back out and couldn’t sleep and was lethargic.”
The actress and mom of two reveals that while she was eager to reclaim her previously healthy lifestyle, the timing of when she finished filming Tully wasn’t ideal.
“I wrapped the film right before Thanksgiving and I was like, ‘Great, I’m not going on a diet now,’ I’m going to do the holidays,” she recalls. “And then when January came around it was just like I could barely walk on a treadmill. My body just didn’t respond like it did the last time I did this. It took like a year and a half for the weight to come off.”
How did she do it? By sticking to a healthy diet and daily exercise — “You know, all that easy stuff,” Theron jokes.
Despite the extra work required to get her back to feeling like herself, Theron says her 40s are her favorite decade and she can’t wait to see what comes next.
“It just feels like everything I’ve ever wanted has come together,” she says. “I have this beautiful family. I’m living the life that I always wanted to lead.”
Tully opens in theaters May 4.