The former reclusive reality star was seen going shirtless in Blac Chyna's Snapchat during the couple's date night on Wednesday.
Kardashian, 28, showed off his tattooed upper body, looking noticeably thinner, while watching his girlfriend cook steaks and salmon from the second story.
Blac Chyna appeared to be continuing her boyfriend's healthy diet by preparing him a protein-packed diet like she's been doing since they started dating in January.
Kardashian has been watching what he eats as well as exercising more after spending two years out of the spotlight feeling down and gaining 100 lbs.
"Forever it seemed like Rob wasn't mentally able to snap out of it," a source told PEOPLE. "Now he seems to do what's best for his health. If he works out with Chyna and eats healthy, that's a very positive thing. If she can get him to feel more comfortable and not embarrassed, that's a huge step for Rob."