October 9, 2026, 3:54 p.m. ET
The results of a recent weight loss study won’t sit well with diet soda fans.
A study by researchers at the University of Liverpool published in August found that diet drinks – such as diet colas and diet soft drinks – are equivalent to water in promoting weight loss and long-term weight maintenance.
Researchers followed nearly 500 overweight or obese adults for almost two years in England.
Participants were randomly selected to consume water or non-nutritive sugary soft drinks daily. The results showed no significant difference in weight loss or weight maintenance between those who drank water daily and those who drank soft drinks daily.
Non-nutritive sweeteners are low- or no-calorie alternatives to sugar – such as aspartame, acesulfame potassium and sucralose – used to sweeten foods and drinks.
Despite findings that diet soda may not have an impact on the scale, there are still some downsides to consuming artificial sweeteners.
Here’s an overview of the study.
Study challenges idea that diet soda causes weight gain
Study participants selected to drink non-nutritive sugary soft drinks (NNS) were allowed to drink diet colas, diet soft drinks, diet fruit drinks, and diet fruit-flavored sugar waters.
They could also consume water, but they had to consume at least two 33-milliliter servings of the eligible beverages per day.
Study participants selected to drink water were asked to refrain from drinking any of the NNS drinks.
Overall, the results revealed a non-significant difference in weight loss between people in the two groups. Both groups also showed sustained weight loss and a decrease in waist and hip circumference.
“These latest findings show that concerns about sweeteners disrupting appetite or causing weight gain are not supported when tested in a rigorous, long-term randomized trial,” one of the researchers, Professor Joanne Harrold, said in a statement.
The research was funded by the American Beverage Association, but the research team was independent of the funder and had complete control over the analysis and reporting of its results.
Diet Drinks Still Pose Health Risks
Yet diet drinks like diet soda still carry health risks, research shows.
For example, research published in July in “Neurology,” the medical journal of the American Academy of Neurology, found a link between consuming higher amounts of certain low- or no-calorie sweeteners and accelerated cognitive decline. The researchers noted that the results did not prove that sweeteners were directly responsible for the decline.
Another 2025 study found that even moderate amounts of sugary and artificially sweetened drinks are associated with an increased risk of liver disease.
Additional research on diet soda shows that it may be associated with weight gain, increased insulin and blood sugar levels, according to the Cleveland Clinic.
Diet soda can also wear down tooth enamel and make heartburn worse, according to Hartford HealthCare.
Gn Health
