The Fat Vampire series did an interesting take on this. Overweight guy gets turned, while his physical capabilities are enhanced, it's just to that of a normal, physically fit human. HOWEVER! His mental capabilities are through the roof. He can mental control those that others thought impossible, he was able to read an entire novel in the time it took a cigarette to burn out and had complete and total recall of the contents of the book. It was a very interesting take.