Food is tremendously personal. To some it is comfort, others a sort of scrapbook of their childhood. To olympians, it is fuel, one of the necessary inputs to a gold medal. Exactly how much of that fuel they take in depends entirely on the sport and division they compete in. Athletes in lower weight classes can eat as little as 1000 calories per day, while those competing in endurance sports consume upwards of 8,000 calories a day. Michael Phelps consumes about 12,000 - all the more remarkable because he exercises enough to burn them off.
More important than the number of calories, is the type. Typically, endurance athletes look to carbohydrates to load up on energy just before they compete. You might be more likely to find something low in carbs and fat on the plate of gymnasts and other nimble athletes. We mortals, however, will have to be content with 1500-2000 calories per day.