On August 26, Conor McGregor, a UFC featherweight champion who has never taken part in a professional boxing fight, will take on Floyd Mayweather, arguably the best boxer of his generation, and a man who boasts a 49-0 record. As bookies have been keen to predict, McGregor has his work cut out.
So, how will the Irishman ensure his diet is preparing him for the "fight of the millennium"?
"We focus on food for performance," McGregor has said in the past. "Giving my body exactly what it needs for the physical training. My diet is usually pretty consistent whether I'm training for a specific fight or not."'
Harley Street clinical and sports dietitian Rick Miller has worked with several combat sports athletes. He agrees that their diet must be rigorously maintained all year round. "Their diets are based on good habits," he says. "It isn't a fad or a crash diet, it's a lifestyle."
What does McGregor's diet look like?
"I don't eat a lot of carbs - if I do it's something like sweet potatoes," he told AskMen.com. "I eat good meat - chicken, salmon, some steak - and a lot of quality greens and some fruits like bananas. I eat eggs - an omelette with my Americano for a late breakfast or brunch.
"Getting enough protein is important when I train, to help build muscle and recover, so I'll supplement with protein shakes. I drink mostly water or coconut water. It's important to stay hydrated - first thing I do in the morning is stretch and drink water."
Miller says perfecting a fighter's diet can take months of testing and trialling ahead of an event. Their diets need to match the energy demands of their training which can change from week to week.
Here are the main pointers to consider.
UP YOUR PROTEIN INTAKE
Martial arts athletes need a medium to high protein diet to build and maintain their lean muscle mass. Muscle requires energy constantly and if an athlete doesn't consume enough protein, they can lose muscle - which is especially bad for a boxer who relies on strength to succeed.
STICK TO YOUR FIVE-A-DAY
The nutrients, minerals and antioxidants found in fresh fruits and vegetables aid repair and recovery and add essential fibre needed in every diet. They are essential components of a healthy diet which can improve longevity of an athlete's career.
CONTROL CARBOHYDRATE CONSUMPTION
A zero carbohydrate diet as McGregor describes doesn't suit everyone. Carbohydrates in the form of wholemeal bread or cereal and root vegetables are beneficial as they provide slow release energy that helps a fighter perform and aids brain function.
The consumption of carbohydrates varies hugely between training so there will be points in their training that athletes require less, and times they require more.
Water affects all body tissue, including around the brain which affects cognitive function. At least two litres should be consumed throughout the day.
When boxers are trying to "make weight", it's common that they will sweat themselves to get rid of water weight. This works to a point but needs to be managed very carefully. If they become too dehydrated, it often takes a long time to rehydrate their bodies, which will hugely affect their performance.
"During training, we work out their average 'sweat rate' so we know exactly how much water their body needs so they won't over-drink," explains Miller.
HEALHTY FATS ARE IN
Walnuts, olive oil, avocado and other sources of healthy fats help the body to recover faster by reducing inflammation. In boxing, blows to the head and concussion are a real concern. Supplements such as protein shakes as McGregor mentions, a joint health supplement and carbohydrate recovery drinks before or after training can be really beneficial.
GET SERIOUS ABOUT SUPPLEMENTS
A good, wholesome diet should always be the first priority. But many athletes reach a stage where their body needs more nutrients than they can consume through their diet.
Supplements should be a temporary measure, used in conjunction with their training plan. Protein shakes, collagen joint supplements and carbohydrate recovery drinks before or after training can be really beneficial.
The main aim of a combat sport athlete's diet is to build and maintain muscle, provide enough energy for training and performance, while keeping weight to a minimum. This, combined with a strict training programme, will leave the body in peak condition for a fight.
A typical day's diet plan
Drink a large glass of water, black coffee or herbal tea when you wake up first thing. This should be followed by 30 minutes slow jogging, jump rope or stretching.
Eat two poached eggs with a slice of smoked salmon on one or two slices of wholegrain toast, spread with smashed avocado. Serve with grilled mushrooms and tomatoes on the side.
Add some mixed berries and a small handful of almonds to a small pot of full cream Greek or goats' yoghurt and sprinkle with cinnamon.
A shredded beef salad with new potatoes and as wide a variety of vegetables as possible. Sprinkle with sunflower and pumpkin seeds and extra virgin olive oil or walnut oil. Follow with a few squares of dark chocolate (at least 80% cocoa solids) and a piece of fresh fruit.
Drink a glass of whole milk or a milk alternative.
Drink plenty of water. Infused water is good during strength training for extra nutrients. Alternatively, opt for water with a hypotonic sports drink.
Drink one scoop of whey or pea protein mixed with water, or a glass of milk. Have a piece of fruit.
Bake a large piece of cod with lemon, herbs and olives. Roast vegetables with olive oil and balsamic vinegar. Eat with wild or wholegrain rice.
Have a cup of rooibos, peppermint tea or more water.