They may fight like brother and sister on The Voice, but when push comes to shove, Adam Levine will always have Christina Aguilera's back -- especially when she's the subject of relentless scrutiny about her fluctuating weight.

Speaking to reporters during a Q&A in New York City Oct. 26, the 33-year-old Maroon 5 frontman said Aguilera's body critics should "grow up" and stop bullying her.

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"The one thing about the culture right now, celebrity culture particularly, is people feel like they can just say nasty things about other people, whether it's Christina or whether it's me," the "One More Night" singer said (via E! News). "She gets a lot and it pisses me off. Of course I have her back and of course I defend her."

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"It's not cool. I've never liked it," he said of celebrity bullying. "I think it's horrible and I'll totally defend her when people say things like that because it's no one's business."

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Levine also dispelled rumors that he and Aguilera, 31, have an ongoing behind-the-scenes feud. "The fights that everyone thought we were having were fictional," the rock star said. "We never hated each other."

This article originally appeared on Adam Levine Defends Christina Aguilera's Weight: "It's No One's Business"