I thought I would answer a question that often get. It is in regards to diet soda and can it make you fat. Well current research has shown that even though soda is techinally "sugar free" and has really nothing but sodium and chemical additives in it, the drink itself can still trick you body into thinking it has sugar in it.
Basically because it still taste very sweet, once you injest it your body senses this "sweet" liquid and goes through the normal cycle of circulating insulin into your blood stream in an effort to get ready to halt the rapid rise in blood sugar. So studies are still underway and should have more long-term and reliable data in future. But for now, keep it in moderation (2 or less per week) and eat your green veggies!