Now that Patrick Dempsey has been dubbed "Dr. McDreamy" he has quite a rep to maintain. HIS sex appeal has viewers gravitating to Grey's Anatomy and suddenly his own anatomy is being scrutinized . So Patrick is taking no chances. He's hikng off his holiday calories in Runyon Canyon in Los Angeles. Fans interested in getting a glimpse of the sexy TV doc will have to keep their eyes open for a scruffy guy in sweats with a wool cap pulled down over his head. Of course, it's also advisable for Patrick to keep in fighting shape just in case his costar Isaiah Washington gets out of hand again.