The Australian actor reveals he adopted a plant-based lifestyle earlier this year (15) after putting a nutritionist's advice to continue eating red meat to the test - and deciding he knew better.

"About six months ago I went and saw a nutritionist to do a blood-diet analysis," Liam tells Men's Fitness magazine. "He basically told me, based on my blood type and all the other different little tests they do, that red meat was good for me, and I should eat a lot more red meat and various other foods. So I started doing that, and the more red meat I ate, the worse I felt."

However, Liam admits his health wasn't the only reason why he started to cut all animal products out of his daily meals.

"After all the information I gathered about the mistreatment of animals, I couldn't continue to eat meat," he explains. "The more I was aware of, the harder and harder it was to do."

The 25 year old turned to his vegan pals for help and he credits Woody with pushing him to give it a try.

"I have a lot of friends who are vegan," he continues. "Woody Harrelson was actually one of the original reasons I became vegan, because he's been vegan for, I don't know, 30 years or something. So, with the facts I was gathering, and then just how I was physically feeling, I felt like I had to do something different, so I adopted this vegan-diet lifestyle. It's been almost five months now.

"There are no negatives to eating like this. I feel nothing but positive, mentally and physically. I love it. I feel like it also has a kind of a domino effect on the rest of my life."

Liam has become such a big fan of eating clean, he's even convinced his older brother, Thor star Chris Hemsworth, to switch up his eating habits.

He adds, "Chris is obviously extremely healthy and has played Thor and has had to work out a lot over the past few years. But he has a lot of digestive issues, and he's constantly trying to figure out what's best for his system. Through talking to me, he's somewhat adapting, I think, to eating more vegetables and more plant-based stuff."

Liam insists he doesn't miss digging into a good steak, but he still has one weakness he hasn't been able to completely conquer - his love of cheese.

"I never get cravings for meat," he says. "The less I eat meat, the harder it is to imagine eating it. I get cravings for cheese, though.

"Every time I'd go to New York, one of my favourite things to do was to go and eat a bunch of pizza. I've had cheese pizza, like, once in the past four months. It was in New York, and it was in the first few weeks of being vegan. I was with some friends, and we'd had a couple of beers - you walk around and there's pizza everywhere, and it's like, 'Ah, God, I've gotta have a slice!'"

Liam and Woody aren't the only famous celebrities who have sworn off meat - Joaquin Phoenix, Natalie Portman, Tobey Maguire, Christian Bale, and Liam's ex-fiancee, Miley Cyrus, have all adopted animal-friendly diets over the years.