But, as The Early Show medical correspondent Dr. Emily Senay reports, some experts are now saying diet soda may be doing the exact opposite: making them gain weight.
Epidemiologist Sharon Fowler, from the University of Texas Health Science Center at San Antonio, presented research data on soda consumption to the American Diabetes Association.
"What we saw was that the more diet sodas a person drinks, the more weight they were likely to gain," she says.