Parker, 26, who was part of the band The Wanted, said he found life in the band very "tough" and can sympathise with his old chart rival's decision to walk away from his grueling schedule, reported Hello! magazine.
"I don't think anyone realises how tough it is being in a manufactured boy band. When Zayn left 1D I totally understood why he couldn't handle it any more," he said.
At the height of their fame, the "Glad You Came" hitmakers were pitched as a bad boy alternative to "One Direction" but Tom insists it was hard trying to live up to their reputation.
"I'm fascinated by history, politics, food, that sort of thing, but we had an image to live up to.