That and being harder to kidnap.

Girl: I can't swim to save my life.
Guy: Me neither - I'm the slowest person ever. I have my bronze medallion, though. That's the weird thing. It was just me and this fat kid in the course together, and he'd always lap me on the timed swims.
Girl: Well, he probably floated more effectively than you did.
Guy: You're right. Fat kids do float better.
Girl: I know. That's their advantage.

-- TJ Baxter's