Married at First Sight "intruder" Mark Kiley underwent an incredible body transformation as he managed to lose five stone before going on the hugely-popular show.The 36 year old customer service manager is gearing up to the join the series as a surprise addition this season, and will be marrying a mystery man. In the run-up to his arrival, Mark has been working hard on his fitness and revealed his amazing achievement on Instagram.The star posted a before and after snap of the results of his new body, as his efforts in the gym have clearly paid off. Showing off his lean new muscles, Mark smiled as he posed and flexed his biceps for the camera.