When you're an athlete, it turns out that maintaining your athleticism can require a pretty hefty diet.

It takes a lot of energy to build up the muscle and keep the energy up, which can result in an eye-watering number of calories per day for some athletes.

Tommy Fury has wowed boxing fans with an order at Five Guys featuring two massive cheeseburgers, fries, and two milkshakes. Now that's a lot of food.

But it seems that the brother of Tyson Fury had no trouble demolishing the two burgers and milkshakes, eating it in pretty short order.

With the amount of training he must do, it's not surprising he has one hell of an appetite!

Instagram/@tommyfury

Fans took to the comments of the boxer's YouTube video - which also vlogged his 48 hours in Milan - to share their thoughts on the mammoth order - which looked delicious, I must add.

One said: "Bro ate 2 days worth of my maintenance calories in one meal."

Another replied: "People don't understand how big he is and how much bigger fighters eat u think 6.5 giants are gonna eat veggies all day."

While a third wrote: "He needs the calories. I bet he burns thousands when he’s working out."

It can take thousands of calories to be able to gain the muscle mass, however, it's worth pointing out that this is a calorie intake for an athlete who is going through an intensive training schedule.

YouTube/Tommy Fury

I'd probably be sprawled out on the sofa in a food coma after eating that much.

And Tommy Fury isn't the only athlete to put away a large amount of food while training.

Former world's strongest man Eddie 'The Beast' Hall became the first person to deadlift 500kg of weight, literally half a ton. That level of strength and building muscle required a formidable diet.

In fact, while training for that particular feat, Hall would put away an astonishing 15,000 calories a day to build the strength up. This could include two breakfasts, a steak, a full kilo of spaghetti bolognese, and half a family-sized cheesecake.

YouTube/Eddie Hall The Beast

Fury and Hall actually swapped diet plans for the day in a video together, with Fury going onto a strongman diet, and Hall having an 'out of camp' boxing diet. The results showed off the enormous amount of calories athletes get through.

The boxer ended up having to put away three steaks across lunch and dinner. That's a lot of red meat.

Meanwhile, The Beast chowed down on a full English breakfast, a Domino's pizza, a massive chicken burger, and eight Krispy Kreme doughnuts.

I need a lie down just writing that, never mind eating it.