Plant fuel: Haye celebrates another KO win. Charlie Crowhurst / Getty Images The images of Rocky Balboa pounding an animal carcass in a meat freezer and gulping down six raw eggs for breakfast have become engrained in boxing culture.

So much so that the thought of an elite-level prizefighter eating anything other than steak and chicken seems unusual.

Enter David Haye, the two-weight world titleist who will take on Tony Bellew in a heavily-hyped pay-per-view dust-up on Saturday, March 4 at the 02 in Greenwich, London.

A look at Haye might not suggest the boxer is vegan, but the Londoner, never one for convention, has been adhering to a strict plant-based diet for three years.

"I have a full-time chef and a good nutritionist who makes sure I get all the minerals and nutrients required," Haye, 36, told The Sun.

"I feel better than ever, I look and feel younger," he added. "People say 'where do you get your strength from?' [But I ask them] where does an ape get his strength from?"

"[Apes are] 20 times stronger than humans and they don't rely on a meat-based diet. They eat plants all day long. It's a myth that you need meat for strength."

Haye turned vegan after looking into the most efficient ways to recover from injury while also researching the "horrible" way animals are treated.

He said: "All roads kept leading back to a plant-based diet."

In combat and strength sports, there is a common misconception that by going vegan people will suddenly become protein deficient, but Gary Turner — a 13-time world champion sportsman — told Business Insider that athletes can get all the protein they need from a vegan diet, providing they eat to caloric needs.

What are the main benefits for an athlete of a plant-based diet?

A vegan diet could result in a longer, healthier life, according to Turner, now a performance expert and personal trainer. "The more we move towards a plant-based diet, the higher our health markers will be," he said. "For animal-based diets, these health markers are lower."

Turner explained that the benefits of eating plant-based foods are not only apparent during training camps, but also last deep into retirement.

"It's also about what happens after an athlete's career. When it comes to health and longevity, there is less opportunity for inflammation and cardiovascular heart disease."

How much protein would an elite-level heavyweight like David Haye need?

The human highlight reel: Will Bellew be the next to fall victim to Haye's hammer? David Crowhurst / Getty Images

"Protein is not a problem at all," Turner told Business Insider. "Sports nutrition studies demonstrate that strength athletes — not even boxers — require 1.3 grams of protein per kilogram of bodyweight. The highest marker would be 2.8 grams of protein per kilogram."

In Haye's brace of fights last year he weighed in at a career high of 103 kg for the Mark de Mori bout, then 101.5 kg for the Arnold Gjergjaj fight. This means his daily protein intake could have been between 132 and 282 grams.

Turner, who noted that "beans and legumes" are excellent plant-based sources of protein, added: "Haye will absolutely not be protein deficient."

Will Haye beat English rival Tony Bellew on March 4?

"If Haye is training right, and I know he is because I know his trainers, he can come in on perfect form," Turner said.

"As always, there are two people in a fight and it also depends on mental state on the night, but on form, Haye should win comfortably."

The winner of Haye against Bellew in London could be thrust into a lucrative showdown with the winner of April's mega-fight between defending world champion Anthony Joshua and former king Wladimir Klitschko.

You can find out more about Gary Turner here.