The source told PEOPLE Monday that Kardashian still "needs to get his eating in check," but has been "more active" lately. "Everyone hopes this time he can turn himself around," the source added.
Kardashian has been spending more time with his family, "which is good for him," the source said. They have helped him move on from his relationship with ex-fiancee Blac Chyna.
"There is a lot of sympathy for Rob — he fell hard for Chyna," the source said. "He's trying to focus on Dream and being a good dad to her. Dream is the sweetest little girl and loves Rob."
PEOPLE's report is backed up by the photo big sister Kim Kardashian posted on Saturday during Kardashian's birthday party. The photo shows a noticeably slimmer Kardashian holding his 1-year-old daughter with Chyna, Dream Kardashian.
"Rob's been taking his bonding time with Kylie to the next level and has been working out with her every other day and seeing the weight fall off has been huge in helping Rob get his confidence back. Kylie challenged and pushed Rob to be better for (daughter) Dream, and that's all the motivation he needed," a source close to Kardashian told the site.
The insider continued, "Rob is staying disciplined and sticking with a strict nutritional program that he's been put on to get his weight down as well, and it makes it easier for him since Dream keeps him pretty active already. He's having a blast chasing her around and seeing her grow up so fast."
Last year, Kardashian retreated from public view after his break-up with Chyna. In the summer, he posted explicit content on his social media pages, and Chyna accused him of posting revenge porn.
Chyna also sued members of the Kardashian family for allegedly playing a role in their spin-off Rob & Chyna getting cancelled. The Kardashian family said it was impossible to film the series after Chyna got a restraining order against Kardashian.
Kardashian has rarely appeared on Keeping Up With The Kardashians and only posts photos of Dream on his Twitter page. He has struggled with weight gain, depression and Type 2 diabetes.0comments
On Saturday, Chyna surprisingly wished Kardashian a happy birthday by posting an old photo of them together with Dream in a movie theater. "Happy Birthday Rob from Dreamy and Chy," Chyna wrote.
Photo Credit: Instagram / @Kim Kardashian