In 493 adults, diet drinks and water were statistically equivalent for weight change across 104 weeks of a behavior program

What the research found

Study (open-label randomized equivalence trial). Jo Harrold, Jason Halford, and colleagues report long-term SWITCH results in the British Journal of Nutrition (doi 10.1017/S0007114526108150; University of Leeds news 1 October 2026). The trial randomized 493 adults with BMI 27 to 35 who regularly drank cold beverages to water (246) or diet beverages sweetened with aspartame, acesulfame-K, and sucralose (247), inside a group behavior program: weekly meetings for 12 weeks, monthly meetings for 40 weeks, then a voluntary year without routine meetings. At week 104, 220 people remained (water 117, diet drinks 103). Mean weight change from baseline was −3.7 kg with water and −4.8 kg with diet drinks; the difference was not significant, which was the equivalence result. Both groups reduced waist and hip measures. Sugar intake fell in both, a bit more with diet drinks. Trial coverage describes ages 18 to 65. The American Beverage Association funded the work; the universities say the team controlled the analysis. Open-label and large dropout limit the claim. Educational notes. This does not mean a diet drink is a health drink, and it does not override other reasons someone might avoid sweeteners.

Evidence level: Clinical trial. This is among the stronger kinds of evidence, but one study rarely settles a question.

Read the original at University of Liverpool and University of Leeds / British Journal of Nutrition