His admission was met with fierce backlash online from vegans and prompted his company ethical clothing company ETHCS to apologise on his behalf.
The company said they were "hurt and let down'" by his actions but insisted it was their "duty to build Tim up again".
While he originally planned to return to veganism, Shieff later admitted in videos that he had completely abandoned his plant-based diet.
This prompted ETHCS, to drop him. Telling a vegan news site: "For a long time Tim had been an inspirational example for veganism, as well as a good friend who has inspired us all, but this lifestyle change was something none of us could get on board with.
"We have all been proud vegans for many years, and promoting the vegan message and ethical lifestyle choices was very important to us all."
"Considering ETHCS was founded on these same principles, we all agreed it would be best if Tim stepped away from the company. And in time Tim agreed too."
Shieff told the Mail on Sunday that going vegan takes "real bravery" and that his departure from the company was a "mutual decision".
"I founded the company as a very passionate vegan, he said. "I have listened to my body and it's guided me on another path for now and my beliefs have changed. My friends who I built the business with are all vegan and remain vegan, so they were shocked by it."