Instead of Transylvania, think Transfatsylvania.

A steady diet of high-cholesterol human blood is slowly sumo-sizing the nation's vampires, according to a new study.

"It's a grave threat to the vampire species," said Dr. Julia Hoffman, professor of undead medicine at UCLA. "As the creatures gain weight, they lose the ability to sneak up on and pursue their victims."

And because vampires can't see themselves in mirrors, many don't even realize they have a weight problem.

"Sure, I noticed my coffin felt a little snug, but I thought the reason I couldn't wrap myself in my cape anymore was because it shrunk in the dryer," said one blood guzzler.

Hollywood has also been forced to adapt. "Twilight Saga" vampire Edward Cullen put on so much weight after filming "New Moon" that the next installment of the series has been retitled "Shamu Moon."

"He loaded up on high school student blood," said a spokesman. "Considering all the junk food his victims ate, he might as well have been drinking pure Crisco."