Heidi Montag Hasn't Told Her Dad About Playboy Photos

'I'm very religious,' 'The Hills' star says. 'I kinda wanted to keep those values a little bit.'

Fans of "The Hills" know Heidi Montag's dad as the gun-toting, cowboy-hat-wearing guy fittingly nicknamed "Cowboy Bill." But he may be surprised to learn that his daughter is the latest Playboy cover girl: Heidi hasn't told him.

"I haven't told my dad yet. I might not tell him," she told "Extra."

"I'm very religious. I'm a big Christian girl. I kinda wanted to keep those values a little bit."

But the fact that she has yet to tell her dad doesn't mean that she's keeping the spread a secret from her mom. In fact, Darlene has been very supportive of her daughter's decision to pose for the magazine. Heidi said, "My mom was so excited. She was just, like, 'Pose! God gave you that body, you show off that cute little thing.' "

Heidi admitted that other than dealing with her parents, her biggest obstacle was getting fit and trim for the photos, for which she didn't bare all. "I love food, too, so I have to work out," she said.

After she debuted the cover last week at the "G.I. Joe" premiere, she explained that she's been using a specialized workout routine to stay in shape. "I worked out very hard for this," Heidi said. "I worked my butt off. [Playboy] kind of had a vision ... and we brought in Matthew Rolston, who is a very well-known, amazing photographer. So, it's more art."