Rob Kardashian's sisters are rallying in support of him amid rumors their lone male sibling is battling major personal issues.

According to People magazine, both Khloe and Kourtney Kardashian have recently taken to social media to post heartfelt tributes to their younger brother.

"Rob is still struggling and it makes the family sad," a source said. "He deals with depression, weight issues and low self-esteem, but that's been going on for a long time."

Rob, 28, began avoiding the public eye after battling depression and gaining over 100 lbs.

In a recent People cover story, Khloé shared of her brother, "He's such a great guy. That's also what's so infuriating. He's charming, charismatic, everything. But I'm like, where is your will to live? Where is your will to live life? Let's be around people."

In recent time, Rob has been a no-show at some of the family's biggest functions, including older sister Kim's star-studded nuptials to rap star Kanye West.

"I've been working on my patience," Khloé said. "I've been really trying. But I have my moments and I do snap ... I can't win life for Rob. I have to wait until [he's] ready to do it for himself."

Not long ago, Rob was rumored to be dating Chris Brown's ex-girlfriend Karrueche Tran, but that seems to have fizzled out amid reports she just wanted to be "friends with benefits."

He has also previously dated Adrienne Bailon, but that relationship ended badly when she publicly accused him of cheating on her. Ditto for his relationship with Rita Ora, which came to a halt amid widespread speculation that she had been unfaithful on multiple occasions.

Word is Rob has yet to meet the newest addition to the Kardashian family, nephew Saint, born earlier this month to sister Kim and West.