“​His travel schedule was gruelling and he often seemed quite beat-up from it, as anyone would be,” a source who worked closely with Bourdain in the past year told People.

“He’d put everything into the shoots and then go back to his room to isolate.”

The 61-year-old host of CNN’s Parts Unknown was found unresponsive on Friday in his hotel room in France by fellow celebrity chef and close friend Eric Ripert.

Bourdain’s mother, Gladys, said Ripert told her that her son had been in “a dark mood these past couple of days”.

Ripert was in France with his friend filming an upcoming episode of Bourdain’s award-winning show.

“It never struck me as peculiar, but it was as if he gave everything to his work and then had nothing, zero, left for himself afterwards,” the source told People.

“He was always very, very tired. He pushed himself extremely hard. Most producers and crew don’t work on every single episode, it’s just too much especially if you have a family. But that wasn’t an option for Tony.”

Still, the source continued, there was never any hint that the star was depressed.

“We never had any sense of depression or mental illness. He was not especially cheerful or engaging, off camera, but it was never rude or ill-intentioned. The guy was absolutely exhausted.”

The former chef spent about 250 days per year on the road travelling to different cities seeking out indigenous cuisine and the locals who make it. He always went home between filming episodes to spend time with is 11-year-old daughter, Ariana, who lives with his ex-wife Ottavia Busia, a mixed-martial-arts fighter, in New York.

In an earlier interview on the road with People, Bourdain said he had no plans to retire.

“I gave up on that. I’ve tried. I just think I’m just too nervous, neurotic, driven,” he said.

“I would have had a different answer a few years ago. I might have deluded myself into thinking that I’d be happy in a hammock or gardening. But no, I’m quite sure I can’t.”

This article originally appeared in the New York Post and was republished with permission.