Study finds diet drinks match water for long-term weight loss

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(The Center Square) – Adults who drank diet drinks, like diet soda, kept weight off just as well as those who drank water over two years, a new study⁠ found.

University of Liverpool researchers followed 493 overweight and obese adults. They randomly assigned participants to drink either water or beverages with low- or no-calorie sweeteners while participating in a weight-loss program.

Those who finished the study lost an average of 10.6 pounds in the diet-drink group and 8.2 pounds in the water group. The difference was statistically insignificant.

States like Florida and Indiana ban people from buying diet soda with Supplemental Nutrition Assistance Program (SNAP) benefits. The federal program helps low-income households buy groceries.

Florida⁠ stopped allowing SNAP purchases of soda, energy drinks, candy and certain packaged desserts on April 20. Its soda restriction includes both regular and diet sodas. The state lists Diet Coke, Coke Zero, and Diet Pepsi among the drinks recipients can’t buy with their welfare benefits. While diet soda has no calories, it also effectively has no nutritional value.

Florida says the restrictions will help recipients eat and drink healthier. Its rules still allow sugary sports drinks like Gatorade and Powerade.

Indiana⁠ also bans regular and diet soda SNAP purchases. Those restrictions took effect Jan. 1. 

The U.S. Department of Agriculture has approved⁠ requests from states to restrict certain SNAP purchases. The Trump administration says the restrictions will improve recipients’ health. Each state’s rules determine which products people can buy.

The Liverpool trial compared diet beverages with water. It didn’t compare diet soda with regular soda or test whether SNAP restrictions improved people’s health.

Participants attended weekly weight-loss meetings over the first 12 weeks, then monthly meetings for another 40 weeks. They could choose to continue for a second year without regular weight-management meetings.

The diet beverages contained sweeteners such as aspartame, acesulfame potassium and sucralose. Both groups consumed less sugar and shrunk their waist measurements during the study.

The World Health Organization advised⁠ against using non-sugar sweeteners for weight control in 2023. It said the evidence didn’t show a long-term benefit in reducing body fat.

WHO called the recommendation conditional. It said that health conditions and sweetener use may impact the results.

Joanne Harrold, Liverpool’s dean of psychology, said in a news release⁠ that “concerns about sweeteners disrupting appetite or causing weight gain are not supported when tested in a rigorous, long-term randomised trial.”

The British Journal of Nutrition published the peer-reviewed study. The American Beverage Association funded the trial.

The authors said the association didn’t design or conduct the trial, analyze the data, or interpret the results. The association reviewed the manuscript, but the authors controlled its final content.

Just 220 of the original 493 participants finished the two-year follow-up. The authors said the low completion rate limited the study. They also said they did the trial at one location in England.

The Food and Drug Administration separately says⁠ sweeteners it approves are safe for human consumption.