Zayn hasn't been shy about talking about his anxiety. However, in his autobiography, appropriately titled Zayn, the singer opened up about his unhealthy dietary habits while on the road with One Direction. Apparently it got so bad that he referred to it as an "eating disorder."

"When I look back at the images of myself from around November 2014, before the final tour, I can see how ill I was," he wrote in the book.

He further explained it to the AP and said, "I realized that I wasn't eating as much just down to the amount of work that we were doing ... our schedule was kind of crazy so we were all over the place."

He also added, "It was just more down to losing track of, you know, actually eating and being super busy and getting caught up with other things that 17- or 18-year-olds do, which normally entails them going out, drinking or partying, so it was a mixture of everything." 

By the end of the interview, he did attempt to downplay it and say that he was never officially diagnosed with an eating disorder and that he was "a bit older and a bit more wiser."

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