Phelps must consume about six times the daily average calories needed by a 23-year old man, around 12,000 per day, according to a report by NBC.
The athlete revealed what a typical day for him entails in terms of food.
For breakfast he starts the day at 5am with three fried egg sandwiches topped with cheese, lettuce, tomatoes, fried onions, and mayonnaise.
In the same meal, he then consumes a five-egg omelet, a bowl of grits (porridge), three slices of French toast with powdered sugar, and three chocolate-chip pancakes, along with two cups of coffee.
The lunch menu is a half kilogram of enriched pasta, two large ham and cheese sandwiches on white bread with mayonnaise, and energy drinks with about 1,000 calories.
After a long day of training his dinner consists of another half a kilo of pasta followed by an entire pizza and another 1,000 calories of energy drinks.
"Eat, sleep and swim. That's all I do," Phelps told NBC.