Rob Kardashian Still Working "Hard" at Diet as He and Blac Chyna Prepare for Baby

She has largely been credited with helping him get healthier, although she herself has been "indulging in what she eats more" during her pregnancy

This year has been a year of many changes for Rob Kardashian—new engagement, new baby and new body.

The 28-year-old reality star stepped back into the limelight several months ago, the the same time he and Blac Chyna stepped out as a couple. He has appeared slimmer than in he has during the previous two years, when he was rarely spotted in public.

 His girlfriend, who became his fiancé in April, has largely been credited with helping him get healthier as well, cooking meals for him and accompanying him to the gym.

However, as evidenced by many videos posted on her Snapchat, Blac Chyna, 28, has herself been "indulging in what she eats more" since the couple revealed in May she is pregnant, a source told E! News exclusively.

"But that doesn't mean Rob fell off track," the source said. "He's still committed [to his healthy diet] and still works out all the time. They work out together too, but she just can't always do the same things as Rob right now. He still works hard!" 

His mother Kris Jenner had said on Keeping Up With the Kardashians in April 2015 that her son has gained more than 100 pounds over the course of a year...which is precisely how many his fiancé wants to gain.

"My goal is to gain like 100 pounds this pregnancy," Blac Chyna had said on Snapchat in June. "I'm going to tear it up and then I'm going to snap back."

Earlier this week, the glamour model and Lashed salon owner asked on Instagram, "Why should I watch my weight when I'm pregnant?"

A photo posted by Blac Chyna (@blacchyna) on Jul 7, 2016 at 12:38am PDT

This will be the first child for Rob and the second for Blac Chyna, who shares a 3-year-old son, King Cairo, with ex Tyga.

"Rob is really excited—it's his first-born, so, sure, there are nerves," the source told E! News. "But they're really happy and he is ready to be a dad."

Rob had showcased his excitement over the baby in photos and videos posted on his and Blac Chyna's Snapchats.

"So today I felt my baby move," Rob said in a video posted on Blac Chyna's Snapchat last week.

Other photos showed Rob hugging and rubbing Blac Chyna's bare baby bump.

The two know their child's sex but have not revealed it publicly. The source also said Blac Chyna plans to have a baby shower, adding, "knowing her, it'll be an all-out party like how she did King's birthday."

Rob and Blac Chyna have also not revealed details about their upcoming nuptials. She "hasn't really talked about the wedding since the baby," the source told E! News.

Meanwhile, the two have also been busy filming scenes for their new E! series Rob & Chyna.

"It's both fun for Chy but a little weird since she's not used to so many people controlling her schedule," the source said. "But they are having fun with it. They've shot already a lot."

Check out Rob & Chyna when the show debuts on E! later this year!