The 41-year-old actress dedicated an entire chapter in her book to the topic, "In Praise of Pubes," saying she doesn't understand why some women choose to undergo permanent laser hair removal.
"It's a personal decision, but I'm just putting it out there: Consider leaving your vagina fully dressed, ladies," she wrote. "Let's be honest: Just like every other part of your body, your labia major is not immune to gravity.
"I know you may think you'll be wearing the same style of shoes forever and the same style of jeans forever, but you won't," she wrote. "The idea that vaginas are preferable in a hairless state is a pretty recent phenomenon. All fads change, people."
Diaz also wrote about her battle with acne, Us magazine reported Friday.
"I mean, I had terrible, terrible, skin," Diaz said. "It was embarrassing, and I did everything I could think of to make it go away. I tried to cover it with makeup. I tried to get rid of it with medication: oral, topical, even the harshest prescriptions. Nothing helped for very long.
"Looking back, I realize that I hadn't needed those prescription drugs, those vials of potions and creams," she wrote. "I hadn't needed to be angry at my skin or feel bad about myself. I had just needed to LISTEN TO MY BODY."