Rob Kardashian recently showed off a slimmer physique, but he says that despite losing a mess of weight, he still has a way to go.

“I still have to lose like 40 to 50 pounds believe it or not,” Kardashian said. “Six months I should be there.”

The reality star blames an unhealthy relationship with singer Rita Ora for his weight gain, saying he packed on the pounds while they were together.

“It’s crazy how this whole year, my whole relationship was only negative,” he said. “All I did was gain f–king 40 pounds and lose so much money.”

Kardashian says he’s working out regularly–although not as much as he was–and has cut back on the alcohol, which is full of empty calories.

“I’m kind of doing my own thing with Lamar [Odom]’s trainer. He’s on salary since he was 19 years old, so he works for us. I’ve been spending time with him,” he said “I’m not really drinking out here in Vegas — I’ve been here since Wednesday and I leave Monday — that’s way too long. But I’m trying to get in a healthy direction.”

Image: Celebuzz.com