The 23-year-old actress explained that she eats a little bit of bone broth -- boiled bones and other animal parts -- in the morning. She said, "What I think is beautiful about it is you utilize the whole animal. You're not just seeking out that perfect cut of muscle meat."
Woodley said bone broth can help with "leaky gut," or, as she described it, "tiny little holes in your intestine," causing substances to leak into the bloodstream.
Woodley mentioned that she eats clay as well -- something she's brought up in past interviews -- to clean heavy metals out of her system. When Letterman asked her whether she eats clay with bone broth, she laughed and joked, "I just make my freak concoction that everyone thinks is weird and eat it."
"Honestly, not too many because I've just been trying to keep my immune system up," she confessed.
The movie opens this Friday.