Rob Kardashian has enlisted his fiancée Blac Chyna to help him lose 22,6kg by May 11. The sock designer has revealed he weighs just under 113,3kg , but has appointed his significant other as his personal trainer to help him achieve his weight loss goal by the time she turns 28. In a series of Snapchat videos posted by Blac, Rob, 29, is seen getting on the scales, which reads 112,6kg, and he says: ''I weigh 113.3 kg and I'm 6'1.'' The Keeping Up With the Kardashians star then tells the camera he'd love to weigh '95,2kg ' or 90,7 kg and the 27-year-old beauty replies: ''I think that's perfect.'' She adds: ''I'm gonna start training him myself.''Do you give me permission to train you for the next five weeks?'' He wasted no time in trying to achieve his goals by getting on a treadmill straight after their weight loss conversation. It was previously reported Blac hired a personal trainer and chef for her fiancé, who popped the question earlier this week, when their relationship was first rumoured in January.Rob has battled for his weight for some time and contracted diabetes, and his sister Khloe Kardashian revealed last month he has been working on his fitness. The 31-year-old beauty said: ''He's working on his fitness journey right now and so, I'm just really happy that he's living this mantra that I preach every day.'' Rob's family are said to be less than thrilled about his engagement, and are reportedly unconvinced it will last as he previously professed his undying love for exes Rita Ora and Adrienne Bailon. He is said to have even told his relatives he had proposed to them, though no engagement announcements were ever made...