I just saw the man on the news. The peculiarities of his eating disorder allow him to - brace yourself - maintain normal weight and cholesterol levels.
His Big Mac feat has been recognized by the Guinness Book.
So the burger count, receipts, etc., appear to be accurate.
The value of knowing the "average," however, is still open to serious question. If his 25,000 receipts show that, by habit, he really did eat, literally, two a day, then that documentation would substantiate the claim without recourse to "statistics."
And we still can't *predict* how many a day he'll eat begining tomorrow.