CHARLOTTE -- You may think you're doing your waistline a favor by choosing the diet version of your favorite soda, but new research says think again.

A study in the Journal of the American Geriatrics Society found that people who drank diet sodas gained almost three times as much belly fat over nine years as those who didn't drink diet soda.

But why? We know regular soda is full of sugar.

"Twelve ounces of soda has 10 teaspoons of sugar, and of course, you're not going to want to drink that. It's just empty calories, so is diet any better? That's the question," said Novant registered dietician Cherly Kuhta-Sutter.

Kuhta-Sutter says the problem with diet drinks is that artificial sweeteners confuse our bodies.

"It does trick your taste buds into maybe wanting more sweets because it is so highly concentrated in its flavoring," said Kuhta-Sutter.

Real sugar can actually help make you feel full. It can send signals to our body that we're full. But some researchers say substitute sweeteners can do the opposite and make you crave more and sweeter foods and even make you hungrier.

Not everyone agrees with this research. And the FDA considers the most common artificial sweeteners like aspartame, sucralose and saccharin as what they call "generally recognized to be safe."

Either way, most dieticians like Kuhta-Sutter try to get their clients to stop drinking any kind of artificially flavored drink.

"When you're looking at diet sodas, if I'm trying to get someone away from sugar and away from sodas, it's a stepping stone. I don't want to keep them there, drinking diet sodas forever. I'd like to get them into sparkling waters, into fruit-infused water,” said Kuhta-Sutter.

There are newer, natural sweeteners like stevia and monk fruit, but they were not included in this study.