You drink diet soda, so you must be healthier. Right? That's what New York Gov. David Paterson is talking about with his proposal for an "obesity tax" — a 15 percent slap on non-diet sugary soft drinks. Think $1 for a Diet Coke, $1.15 for a Coke. There's just one problem: Studies have found links between drinking diet sodas and obesity and diabetes. A 2005 study at the University of Texas Health Science Center, San Antonio, and separate studies released in 2007 at the University of Alberta in Canada and the University of Massachusetts found that diet soda drinkers were...