I'm not totally sure. If a fat person was bitten then they would stay that way, right? But yeah, once they become Vampiri#From Dracula to Buffy... and all creatures of the night in between. can't gain any weight. Though theres nothing that says they all have to be skinny.
i think they would turn perfect like it says in the books. thats how Vampiri#From Dracula to Buffy... and all creatures of the night in between. lure in their victims they are perfect and everyone falls in Amore with their beauty so therefor would do anything for a vampire o go anywhere with a vampire!