My (adoptive) Mom has been slender her whole life. She's a total carb addict -- she can eat cake and ice cream and not put on a pound. She's also been a diabetic with high blood pressure since her mid-thirties, has had awful arthritis, irritable bowel syndrome, and GERD. Ten years ago she was diagnosed with congestive heart failure and has been on various medicines, including beta blockers, since then.

In other words, she's collected the whole set of the Diseases of Civilization, minus obesity. I understand why you're asking this -- heaven knows I used to ask myself that all the time -- but now I know: Skinny isn't the whole picture; not by a long shot.