But there's a catch. 

Fizzy water obesity study
Credit: jarih / Getty Images

Though it may seem light and healthy, you may be out of luck if you've been drinking carbonated water instead of soda to help your health: the carbon dioxide in fizzy drinks may cause obesity.

Researchers at Birzeit University found that rats that were given fizzy water to drink gained more weight than those who only drank flat water. The fizzy water itself doesn't contain some addictive that made them gain weight but instead, the carbon dioxide in the carbonation gave them the urge to eat more.

In fact, the levels of the “hunger hormone” ghrelin – which your stomach secretes when it's empty – were significantly elevated in the rats who drank the fizzy water, prompting them to eat 20 percent more than the other rats.

The rats that drank the fizzy water also showed a build up of fat in their organs, which is one of the symptoms of chronic obesity in humans.

The researchers subsequently ran similar tests on human volunteers. The participants who drank sparkling water had ghrelin levels six times higher than those who drank only flat water.

As a result of the study, Tam Fry, a spokesperson for the UK’s National Obesity Forum said in a statement that, “The Department of Health must now curb the use of any chemicals that impinge on health and that should include carbon dioxide if this effect is replicated in further studies."

If you’re prone to indulging in carbonated water, don’t panic just yet: The research is still in its very early stages, with the worst symptoms only showing up in rats so far.

But as drinks like soda are being taxed in more and more states, and more Americans are enjoying bottled water over carbonated drinks, maybe it’s best to stick to plain old water until science can give us the full story on carbon dioxide’s effects on our health.