Rob Kardashian is fuming over Kim's recent interview with Rolling Stone.

Rob Kardashian Skips His High School Reunion As His Weight Becomes An Issue On 'KUWTK'

During the interview, Kim acknowleged her brother's weight gain, and said if he was doing meth, as opposed to marijuana, he would be "skinny."

“Rob and Kim had been cool again and were getting along,” an insider told Us Weekly on Friday. “Now he’s furious at her again for her comments to Rolling Stone. He was been bitching her out on her phone. He’s mad — pissed as hell."

Kim Kardashian Opens Up About Rob To 'Rolling Stone Interview'

“Rob has blocked Kim on his phone,” a second source revealed. “He doesn’t want to hear what she has to say. He says there’s no excuse she could possibly have for saying that. He will not forgive her."

“It’s not that mysterious, what’s happening with Rob. He has gained weight. He feels uncomfortable being on the show, and that’s OK,” Kim told Rolling Stone earlier this week, according to a report by Us Weekly.“Do I think he smokes weed, drinks beer, hangs out and plays video games with his friends all day long? Yes.”

When the magazine wanted to know if Kim thought “it’s not more like hookers and meth at the Ritz,” she denied any such drug use.

“No, no,” she said. “Or he’d be skinny.”

Keeping Up With The Kardashians airs Sundays at 9 p.m. on the E! Network.