Zero-Sugar Drinks Help Participants Lose More Weight Than Water

A new study claims zero-sugar beverages can actually assist with shedding pounds and hold their own against plain water. Researchers set out to determine if regularly consuming diet drinks might block progress or make it harder to keep weight off. They split overweight adults into two distinct groups, sending one team down a path of drinking only water while the other sipped artificially sweetened options throughout their entire journey. The sweeteners tested included aspartame, the same chemical found in popular sodas like Diet Coke and Diet Pepsi.

For two years these participants followed a behavioral weight-loss program designed to help them drop pounds and keep them off. They received guidance from nutritionists and slowly ramped up physical activity until they were exercising for an hour six days each week. The results showed both teams weighed less than when the study began, but diet soda drinkers lost 25 percent more weight compared to those who stuck strictly to water. These findings suggest sugar-free drinks might offer a low-calorie method to satisfy cravings for sweetness, potentially making weight-management plans easier to stick to long-term.

Experts caution that more research is needed before declaring victory, noting some studies have linked artificial sweeteners to long-term health issues such as diabetes and heart disease. A two-year experiment comparing diet drinks with water during a calorie deficit found that people drinking artificially sweetened beverages did not gain more weight than those drinking water. Artificial sweeteners like aspartame and sucralose are about 200 times sweeter than sugar and contain zero calories. They appear typically in diet sodas as well as sugar-free energy drinks including Celsius.

While it has long been clear that sugar raises the risk of heart disease, obesity, and diabetes, the long-term effects of artificial sweeteners especially regarding weight loss remain unclear. In an August 2026 study published in the British Journal of Nutrition, researchers tested the ongoing debate about whether non-sugar sweeteners actually help with long-term weight control. Experts studied 493 adults between ages eighteen and sixty-five, and their body mass index ranged between twenty-seven and thirty-five, categorizing them as overweight or obese.

Of the subjects, two hundred forty-six were randomly assigned to drink water while two hundred forty-seven were assigned to drink diet or sugar-free drinks. Participants were instructed to consume at least two three hundred thirty millilitre servings, roughly 2.7 cups, every day of their assigned beverage. The zero-sugar group had a choice of twenty commercially available beverages, including diet colas, diet carbonated soft drinks, diet fruit drinks and diet fruit-flavored waters. The main artificial sweeteners in them were aspartame, acesulfame potassium and sucralose. These are commonly used in Diet Coke products and zero-calorie sweeteners such as Splenda.

People assigned to water were told to avoid artificially sweetened beverages entirely, including zero-calorie sweeteners added to hot drinks. The diet-drink group could still drink water in addition to their assigned beverages. Participants then entered a weight loss program featuring three stages: active weight loss, supported weight maintenance and no weight management sessions. A chart comparing body weight over weeks fifty to one hundred four shows two groups: one that drank water and another drinking non-nutritive sweeteners otherwise known as artificial sweeteners. The artificial sweetener group lost slightly more weight by the end. After two years both groups weighed less than what they started at the beginning of the trial.

Water sippers shed roughly 8.2 pounds from their starting weight. Those who relied on diet beverages dropped 10.6 pounds. That is a gap of 2.4 pounds between the two camps. The program ran in one-hour group sessions each week, led by a nutritionist who guided participants on eating behaviors and structured physical activity. For the first year, everyone was told to ramp up their movement by adding ten minutes of walking daily until they hit sixty minutes on six days every week. Researchers watched this progress with fitness trackers monitoring step counts and activity levels.

From weeks zero through twelve, participants showed up for weekly nutrition sessions. Both groups lost weight fast during this opening phase. Then, from weeks thirteen to fifty-two, the schedule shifted to monthly check-ins to help maintain that shed mass. The water group hit its lowest point at week forty-four. The diet-drink group bottomed out earlier, at week thirty-six. And from weeks fifty-three through one hundred and four, they continued their journey on their own while tracking what they drank. By the final week, both groups stayed significantly lighter than when they started.

After two years, both cohorts weighed less than their initial mass. Water drinkers lost about 8.2 pounds from where they began. Diet-drinkers lost 10.6 pounds, a twenty-nine percent difference in total loss. Both groups ended up with smaller waist and hip circumferences than at the start, trimming about two inches off their waists. Researchers also ran detailed body-composition scans on a small subset of forty-eight participants. The data showed both groups shed fat and some lean tissue at similar rates. They took fasted blood samples to check blood pressure, glucose, cholesterol, and insulin levels as well.

Total cholesterol ticked up slightly in the diet-drink group. A long-term blood sugar measure called HbA1c rose a bit with diet drinks but remained steady for water drinkers. Diastolic blood pressure, that lower number in a reading, fell more among those drinking water. Yet these results leaned on just fourteen to sixteen people per group. None of the differences reached medical significance. While the diet-drinkers lost more weight overall, researchers could not claim diet drinks drove greater long-term loss. The groups were considered equivalent regarding their final weight outcomes.

The study also tested a long-held theory about artificial sweeteners confusing the body's link between sweetness and calories, potentially spiking appetite and making people eat back what they thought they burned. The findings showed no meaningful difference in hunger between the two groups. One major limitation was that while 493 people started, only 220 finished by the one-hundred-and-four-week endpoint. By the end, there were 117 in the water group versus 103 in the diet-drink group. Researchers ran statistical analyses designed to handle missing data, and these also found no significant weight loss difference between the beverages. Enrollment happened between 2016 and 2021, so the COVID-19 pandemic disrupted some follow-up visits. The trial found no evidence that choosing diet drinks over water derailed their progress.