Kylie Jenner poses with sisters Kourtney and Khloe Kardashian as they show off their slim figures in identical waist trainers

Kylie Jenner posted a picture of herself and sisters Kourtney and Khloe wearing matching waist trainers on Instagram on Monday evening. 18-year-old Kylie captioned the image with the words: 'Posted up with my babes getting our waists right with @premadonna87 @waistgangsociety get your cute little holiday trainer from whatsawaist.com.'