Mike Tyson has revealed that he has ditched his plant-based diet and turned to stem-cell treatment ahead of his exhibition bout against Roy Jones Jr. this weekend.

After retiring from the sport in 2005, Tyson gained weight rapidly, tipping the scales at 27 stone at his heaviest. At this point, he opted to change to a plant-based diet in an attempt to slim down.

However, prior to stepping into the ring for the first time in 15 years on Saturday in Los Angeles, the 54-year-old confirmed that he has now reintroduced meat into his diet in order to build up his strength.

“I stopped because of the training and because of what I wanted my body to look like and the strength that I wanted to possess.

I only eat elk and bison - wild stuff - and I’m starting to feel fit

“I realised the stuff that’s good for other people - like kale, vegetables and blueberries - for me is really poisonous…. Kale will kill me!” he said on Joe Rogan's podcast, as reported by The Mirror.

As well as his diet, Tyson has stepped up his training, and looks in remarkable shape for his comeback.

Detailing his daily routine, Bodhizone states that the youngest-ever heavyweight champion runs up to five miles in the morning, spars before and after lunch, completes multiple strength training sessions, does an hour on the bike and works on his boxing technique in the gym.

Tyson has also told reporters that he has taken the unusual step of trying stem-cell treatment in recent weeks, and is already feeling the benefits.

"Six weeks of this and I’d be in the best shape I’ve ever dreamed of being in.

"As a matter of fact, I’m going through that process right now," he said, as reported by the New York Post.

Tyson's adjustments appear to have worked. 'Iron' Mike weighed in at 220.4lbs on Friday.

This is lighter than he was for his first world title fight in 1986, when he dispatched Trevor Berbick inside two rounds to be crowned champion at the age of 20.

The iconic heavyweight has certainly taken this fight seriously, and it is easy to understand why. He will be facing a formidable foe in Roy Jones Jr. who only stepped away from the squared circle two years ago.

Jones Jr. won titles in four separate weight classes during his career, including at heavyweight in 2003. 

Both men appear to be prepared. Now we must wait for Saturday night to see who comes out on top in this highly-anticipated match-up.