Since he left One Direction, Zayn has been public with his battle with anxiety. But the singer also says he was struggling with even more behind-the-scenes ? a possible eating disorder. Zayn made the revelation in his new autobiography "Zayn," out Tuesday via Penguin Random House. The 23-year-old writes in the book "When I look back at the images of myself from around November 2014, before the final tour, I can see how ill I was," calling it an "eating disorder.