I have to agree with most of the discussion, it isn't that big of a deal. When you are training consistently with a specified regiment day in and day out, your body adapts to a certain level.
It is the same with eating, if you more or less "reset" your metabolism through a strict regiment and compliment that with a grueling training regiment like the elite athletes have, then most of them will consume 4-6K calories per day without seeing a detrimental effect to their performance. Especially because to be able to consume 4-6K calories of "clean" food is monumental.
It's not easy, but it is possible for any type of athlete to be able to do this, it just takes dedication and a heavy knowledge of your body and nutrition