More on Diet Sodas...

Pop quiz! What's the single biggest source of calories for Americans? White bread? Big Macs? Actually, try soda. The average American drinks about two cans of the stuff every day. "But I drink diet soda," you say. "With no calories or sugar, it's the perfect alternative for weight watchers...Right?"

Not so fast. Before you pop the top off the caramel-colored bubbly, know this: guzzling diet soda comes with its own set of side effects that may harm your health--from kickstarting kidney problems to adding inches to your waistline.

Unfortunately, diet soda is more in vogue than ever. Kids consume the stuff at more than double the rate of last decade, according to research in the American Journal of Clinical Nutrition. Among adults, consumption has grown almost 25%.

Here's something you didn't know about your diet soda: It might be bad for your kidneys. In an 11-year-long Harvard Medical School study of more than 3,000 women, researchers found that diet cola is associated with a two-fold increased risk for kidney decline. Kidney function started declining when women drank more than two sodas a day. Even more interesting: Since kidney decline was not associated with sugar-sweetened sodas, researchers suspect that the diet sweeteners are responsible.