This study is focused on people who were already regular diet soda drinkers and wanted to shed some pounds.
Researchers wanted to answer the question -- for this group of people, is it better for their weight loss to drink water or diet soda?
The study was done by researchers at the University of Colorado and will be published in the journal Obesity.
The researchers split up about 300 diet soda drinkers into two groups. One group was allowed to continue drinking diet soda while they dieted. The other group had to give up diet sodas and could only drink water. both groups were put under a weight-loss program -- but calories were not tracked.
The group that drank water only, lost nine pounds over 12 weeks but the group who continued drinking diet soda lost more -- 13 pounds on average over 12 weeks, amounting to a four pound difference.
Researchers say the most likely explanation is willpower. It's harder to maintain a weight-loss diet while also trying to kick another habit, like giving up diet soda, if that is what you've always done.
It is also important to note -- this research was funded by the American Beverage Association and researchers who work for the beverage industry.