Credit: Rob Kim/FilmMagic

No pregnancy pig outs for this diva!

Mom-to-be Beyonce is not overindulging with her diet during her very first pregnancy, she tells Katie Couric in a new 20/20 interview airing Friday night.

"I've been really conscious [about food]," the "Countdown" chanteuse, 30, says. "I've been trying my best not to lose control," adds the star, whose taut, curvy bod is legendary.

"Because I've met so many people that say, 'My second baby, my third baby, I've learned my lesson,'" she explains of other moms who struggled to lose weight post-baby. "So i haven't been going crazy. I know it's important that I don't lose myself."

Married to Jay-Z for three years, the Grammy winner gushes to Couric about welcoming the baby and becoming a mom. "It's exciting! I know it's gonna be difficult at times," she admits. "I know that, like my mother, I'm gonna get on my child's nerves [but] I'm just ready! I'm ready for the next chapter."