02/22/2013 04:02 pm ET

Khloe Kardashian On Rob Kardashian's Weight Loss Goal: 'I Believe In You'

On Sunday's episode of "Kourtney & Kim Take Miami," we learned that Rob Kardashian has put on 40 pounds since his split from Rita Ora.

"All I did was waste a lot of money and gain 40 pounds," Rob, 25, told his sisters of the tumultuous relationship. "I need to focus on me. That’s all I wanna be about."

And now it looks as if Rob is determined to follow through with his weight-loss goal.

"Goodness I can cook! Swordfish, kale salad, asparagus," he tweeted Thursday, with an Instagram photo of his healthy dinner.

"Another fat boy breakfast. Let's go! 5 mile run next. 50 pounds gots to go!" he shared in another tweet, along with a picture of eggs and grapefruit.

Fortunately, he already has one strong supporter in his older sister Khloe, who replied, "I believe in YOU."

Khloe, 28, recently opened up about her own weight, proclaiming that she's confident about her curvy figure.

"A few years ago I lost 30 pounds, and people still wanted to criticize. And honestly, I’m happy with myself if I’m a little heavier," Khloe told Glamour magazine. "I realized: 'Why am I trying to conform to someone else’s idea of beauty?' I think I’m beautiful either way."



The Kardashians