"There were so many nights where I would wake up in the middle of the night like, 'Oh my God! I have to be on camera tomorrow, and I'm so stressed out. How do I lose 10 pounds in eight hours?'" she shared.
Prepon said she suffered from bloating and low energy and began a cycle of crash diets, adding that she starved herself and even took hormone injections to lose pounds. According to the Orange Is the New Black star, none of those tactics were successful in keeping the weight off.
Prepon credits clean eating with changing her life and created "The Stash Plan" with nutritionist Elizabeth Troy.
"Twice a week you have these easy cooking sessions," she said, explaining the 21-day program. "You cook a stash, put it in your fridge and every morning you build your meals from it. That really is the crux of it."
Prepon's New York Times best-selling cookbook with Troy, The Stash Plan: Your 21-Day Guide to Shed Weight, Feel Great, and Take Charge of Your Health, is available now, but fans still have to wait to see her return on Orange Is the New Black. The new season will be available for Netflix streaming on June 17.
In the season three cliffhanger, viewers saw Piper (Prepon) in dire straits. While she didn't spill any spoilers, Prepon did fill us in on how their behind-the-bars look brings out more authentic performances.
"We're stripped of makeup. We're all wearing the same khaki jumpsuits," Prepon said. " A lot of people get into character by their wardrobe and their shoes and hair and makeup and everything else. Having that stripped away, and having it just be the moment to moment between my fellow actresses is unreal! It's awesome! I think [next season] is one of our best seasons."