Not only has Rob Kardashian been slowly re-emerging in public after hiding out for years, the 28-year-old sock designer also looks noticeably slimmer. Ever since he started dating model Blac Chyna, Rob has been hitting the gym and eating healthier resulting in a reported 40-pound weight loss. 

So what exactly is the former "Keeping Up With the Kardashians" star doing to shed the weight? TMZ reports that Chyna has her boyfriend on a strict no carb diet. In addition, he's also cut out red meat, fast food and works out five times a week. 

The outlet also reported that Chyna and Rob made a "no cheat days" pact and have been motivating each other to stay healthy. 

According to Us Weekly, shortly after Chyna and Rob started dating she hired an online personal trainer and chef to help keep them on track. 

“Everything about him has changed,” a source told the outlet. “She’s been so good for him.”

Chyna recently proved just how serious she is about Rob's weight loss when she took several Snapchat videos of her going through his cabinets and criticizing his food choices. In one video, the mom of one held up a box of Raincoast Crisps cookies, asking, "Babe, what is this? What is that? What the f---." In a second video, she held up a tub of Sharon’s Sorbet, and said, “Are we supposed to eat this?”

As previously reported, it's believed Rob gained about 100 pounds over the course of three years following his split from singer Rita Ora. His weight gain led Rob to shy away from the public and he also stopped filming the family's E! reality show. Rob's weight gain also led to him being diagnosed with type 2 diabetes in December.