Sodas such as Diet Coke (KO) and Diet Pepsi (PEP) are wildly popular by those trying to trim down -- and with zero calories, who’s to blame them? The problem with diet soda is that the artificial sweeteners they’re made from are not natural, and their effects are still not entirely understood by the medical community. This might help explain why drinking even one diet soda a day has been linked to obesity. Recent studies have also shown that drinking diet soda can increase your risks of heart attack and stroke.

So what's your best bet when you want to hydrate in a healthy manner? Water. Chances are, you'll still be supporting the same companies; while Coke and Pepsi both experienced shrinking market shares in 2011, Dasani bottled water (a Coke product), experienced an 11% boost. In fact, soda companies have suffered such a decline in sales that they're increasingly turning to other products to pick up the slack. PepsiCo, for example, is currently preparing to sell its very own yogurt brand.