AceShowbiz -

Rob Lowe said he knew some "dark secret" about Justin Bieber. Appearing in an episode of "Oprah Prime" on Sunday, April 6, the former teen idol admitted that he liked Bieber's music. "I have tremendous empathy," he said of the "Confident" singer.

"He makes really good music, he does, but I think he knows the dark secret, and the dark secret is 80 percent of his audience doesn't give a s**t about the music. And he knows it. It bums him out," Lowe explained.

"They care about lemming-think, and their girlfriends and who's oohing and aahing and screaming. It has nothing to do with what he's doing as an artist. He is the guy who is standing in front at a moment that they're going through a developmental thing. It's natural, it's all great, but if it wasn't him, it would be somebody else, like it was me," the former star of "Parks and Recreation" continued.

In the interview, the actor also mentioned how rehab helped him deal with substance abuse. "I loved it," he said. "I don't know what that says about me. I didn't love the fact that I had to go and it was absolutely painful, but I liked the science. I couldn't have gotten sober without rehab because I needed the science. I needed to [learn about] addiction and what it does to your body and all of the research and the things like that."

Lowe is now promoting his memoir "Love Life" which is out on Tuesday, April 8. His first book "Stories I Only Tell My Friends" was released in 2011.