Credit: Jon Kopaloff/FilmMagic

Jessica Simpson's tastes are quite different now that she's eating for two.

"I had a buttered Pop Tart this morning," the pregnant 31-year-old tells Extra. "I'm eating a lot of stuff that I ate in my childhood. Kraft Mac n' Cheese, Pop Tarts, Cap'n Crunch. Everything's filled with sugar."

The Fashion Star mentor adds that she isn't afraid to "give in to my cravings. "I'm like, 'Yeah, I can do it. We'll worry about the rest afterwards.'"

Luckily, Simpson hasn't experienced any morning sickness. "Everybody comes up to me and asks me, 'How's the nausea?' and I'm like, 'I don't have any!'" the singer says, though she's "definitely eating a lot of Tums -- I have the reflux and acid going on."

Due later this year, Simpson says she and fiance Eric Johnson, 32, still don't know the sex of their baby. "I feel like it's already going to be a shock. Like, 'Whoa! I just pushed that out!' You know?"

The couple has some names that they're "throwing around" but Simpson says they're keeping them "on the down low" for now.