Fans of "Keeping Up with the Kardashians" know that Rob Kardashian has reportedly struggled with weight problems, depression and severe anxiety for quite some time. There have been rumors that he has a drug problem as well.

In an interview with Rolling Stone for the magazine's July issue, Kim Kardashian West opened up about her 28-year-old brother. She revealed that his drug of choice is marijuana.

"It's not that mysterious, what's happening with Rob," the pregnant reality star told Rolling Stone. "He has gained weight. He feels uncomfortable being on the show, and that's OK. Do I think he smokes weed, drinks beer, hangs out and plays video games with his friends all day long? Yes."

Us Weekly reports that when Rolling Stone asked the "Selfish" author if she thought "it's not more like hookers and meth at the Ritz," Kim immediately shut down that possibility.

"No, no," she said, laughing. "Or he'd be skinny."

Kim has always taken a "tough-love" approach when it comes to Rob's condition.

"Everyone licks Rob's ass and does whatever he says," Kim said to her mother, Kris Jenner, on the April 5 episode of "Keeping Up with the Kardashians." "It's just like, at some point you just have to give it up. We all make his life so easy."

Her lack of empathy toward him is probably why Rob compared her to Rosamund Pike's "Gone Girl" character in a vulgar March Instagram post.

Rob has become a recluse, and many believe it is due to the media's focus on his weight. He was last seen in public June 17 grabbing dinner from an In-N-Out restaurant near his home in California.

A source close to the family says that Rob has been experiencing high blood pressure and numbness in his hands due to his 300-pound weight gain, and the Kardashian family plans to force him into a weight loss rehab center, reports OK! Magazine.

Read more about Kim's thoughts on Rob, her life as a teenager, her beliefs and more in the July issue of Rolling Stone magazine that hits newsstands Friday. Kim appears in a pinup-worthy cover shoot with famed photographer Terry Richardson, showing off her assets in a sexy, nautical ensemble.