Kim Kardashian blames her brother Rob's 50-pound weight gain on his ex-girlfriend Rita Ora.
"Kim's furious about how Rita treated Rob," a source told Now. "It's a tricky situation because Jay-Z discovered Rita and she's firmly entrenched in Kanye West's musical circle, but Kim hates seeing her brother upset."
Rob, 26, had a rippling physique when he first starred on "Keeping Up With the Kardashians" in 2007. He remained in phenomenal shape until last year, around the time he broke up with singer Rita Ora.
On the most recent season of their reality TV show, Rob admitted he had gained 50 pounds after his rocky relationship with Ora ended.
He said he began overeating compulsively and stopped working out because he was depressed that Ora had kept their relationship a secret to maintain her public image as a single gal. Rob also claimed on Twitter that Rita had cheated on him "with 20 different dudes." He has since deleted that tweet.
Rob's weight has been a running theme on "Keeping Up With the Kardashians," and his sisters Kim, Khloe and Kourtney have all expressed concern that Rob's weight has made him more reclusive and angry.
Kim reportedly blames it all on Rita Ora's poor treatment of her only brother. "She doesn't think he's been the same since the split and she blames Rita," said a source.
For exercise, she runs and does weight-training. She said losing the baby weight was the hardest thing she had ever done, but also one of the most rewarding.
"I work out so hard and this was such a challenge for me but I did it!" said Kardashian, 33. "I'm so proud of my accomplishment."