Board Thread:Lore Discussion/@comment-26861588-20150814151511/@comment-25267426-20150814182800

He just gets bigger the more he eats. Up to the point where he can eat large sections at once.

https://www.reddit.com/r/teslore/comments/1t04yz/how_does_alduin_eat_the_world/

http://www.imperial-library.info/content/fight-one-eating-birth-dagon