Diet beverages containing sugar substitutes performed about as well as water in supporting weight loss among adults with overweight or obesity, according to a two year randomized trial. The findings challenge concerns that artificial sweeteners automatically interfere with efforts to lose weight.

Researchers led by the University of Liverpool in England enrolled 493 adults between 18 and 65 years old. Every participant had a body mass index between 27 and 35, placing them in the overweight or obese range.

Half of the participants received 22.3 ounces of water each day. The other half received the same daily amount of beverages containing non nutritive sweeteners, equal to approximately two cans, during the 104 week study period.

Participants assigned to the sweetened beverage group could select from diet sodas, flavored waters and fruit drinks with few calories. Aspartame, acesulfame potassium and sucralose were the primary sweeteners used in those products.

After two years, participants drinking diet beverages had lost approximately 10.6 pounds. Those assigned to drink water lost about 8.2 pounds during the same period.

Both groups maintained a meaningful amount of weight loss across the two years, according to the researchers. That included the final year, when participants were no longer receiving regular support for weight management.

Participants in both groups also lost inches around their waists and hips while reducing body fat. Researchers found no meaningful difference between the diet beverage and water groups for those measurements.

Total cholesterol remained within the healthy range in both groups. The findings were published in the British Journal of Nutrition.

Alix Turoff, a registered dietitian in New York City who was not involved in the research, cautioned against crediting diet beverages for the results. “The study does not show that diet beverages themselves caused the weight loss,” she told Fox News Digital.

“Everyone in the study was participating in a structured weight-management program that included nutrition counseling, behavioral support and physical activity recommendations.” Turoff said the value of diet beverages was based on substitution rather than any magical metabolic effect.

The trial compared diet beverages with water rather than drinks containing sugar. That design allowed researchers to examine whether the sugar substitutes appeared to hinder weight loss efforts.

“If someone normally drinks 250 calories of regular soda and switches to zero-calorie soda, then they’re saving calories,” Turoff said. She also emphasized that the findings do not mean water and diet soda are nutritionally identical.

The study found no significant differences between the groups in hunger or sugar intake at the end of the trial. Turoff said that result matters because artificial sweeteners are sometimes feared to increase appetite or encourage compensatory eating.

Turoff still recommended water as the primary choice for hydration. At the same time, she said people should not fear diet drinks because of the belief that they will automatically prevent fat loss or cause weight gain.

The research had several limitations, including its location at a single site in England. Researchers did not collect information on race or ethnicity, limiting how broadly the findings can be applied.

Only 220 of the 493 participants who began treatment completed the assessment at 104 weeks. Participation in the second year extension was voluntary, so those who continued may have been more motivated or more likely to follow the program, Turoff noted.

The American Beverage Association funded the trial. The study authors stated that the association did not participate in designing the research, analyzing the data or interpreting the results.