KEY POINTS:
Michael Phelps dives into breakfast like he dives into an Olympic pool, knocking back a phenomenal amount of food to power his "superhuman" lungs, legs and arms through the first part of his swimming day.
The top Olympian of all time after winning a record-breaking 11th Olympic gold
medal - including five at Beijing - has revealed the source of his power: he eats an eye-watering 12,000 calories a day.
Loaded with this mountain of food, packed with cheese and eggs for protein and an avalanche of carbohydrates, Phelps is charged up with over four times the daily median energy intake of New Zealand men.
But while most people would uncontrollably pack on weight at this intake, even if they could muster the appetite to chow it down, Phelps' punishing five-hours-a-day training regime, six days a week, is more than enough to burn it off.
For breakfast, he fires up his energy-factory body with a starter of three fried-egg sandwiches with cheese, lettuce, tomatoes, fried onions and mayonnaise.
Two cups of coffee follow, to keep up the fluids, and he settles into the main course: a five-egg omelette, a bowl of grits (a coarsely ground corn porridge), and three slices of french toast, sprinkled with extra sugar. Dessert is three chocolate-chip pancakes.
For lunch, Phelps munches through 500g - a whole packet - of enriched pasta and two large ham and cheese sandwiches made of white bread and with plenty of mayo. As for fluids, it's a 1000-calorie energy drink.
Dinner brings another half kilogram of enriched pasta, an entire pizza and another big draught of energy drink.
"Eat, sleep and swim, that's all I can do," Phelps told NBC television.
Dietitian Rob Quigley said Phelps would need every bit of the energy he consumed; some athletes in endurance events, such as Tour de France cyclists, needed even more.
"For someone like him, who is clearly training at superhuman levels, he needs to match that with an outrageous energy intake."
Mr Quigley said some Tour de France riders were hooked up to a nose-to-stomach feeding tube while they slept because they did not have enough time during the days and days of pedalling to eat sufficient energy.
Phelps was unlikely to be building up any future health problems from his diet, such as bad cholesterol levels, Mr Quigley said.
In his favour were "extreme physical fitness, his good bodyweight, he won't drink, he won't smoke, he's young".