Diet drinks work as well as water for weight loss, major trial finds — SkimNews
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- The SWITCH trial enrolled 493 adults with overweight or obesity over 104 weeks, finding NNS beverage drinkers lost a similar amount of weight to water drinkers (−4.8 kg vs −3.7 kg; nonsignificant difference).
- Researchers at the University of Liverpool found no clinically meaningful differences in blood pressure, cholesterol, or appetite regulation between the NNS and water groups across the full two years.
- The American Beverage Association funded the trial, though the research team stated they operated independently and retained full control over analysis and reporting.
- The study tested beverages containing aspartame, acesulfame-K, and sucralose at levels well within European Food Safety Authority safety thresholds, with both groups showing reductions in waist and hip circumference.
- Both groups maintained weight reductions across all 104 weeks, including the final year when participants no longer received behavioral support, and saw improvements in body composition and metabolic biomarkers.
- Professor Joanne Harrold said the findings contradict concerns that sweeteners disrupt appetite or cause weight gain and could help inform future WHO guidance, which currently advises against non-sugar sweeteners for weight control.
- Sugar intake fell in both groups, with a slightly larger reduction among participants drinking NNS beverages, according to the peer-reviewed results published in the British Journal of Nutrition.
Why it matters: The WHO currently advises against non-sugar sweeteners for weight control based on observational uncertainty; this two-year RCT from the University of Liverpool, the longest and most comprehensive to date, now provides the kind of randomized evidence that could shift that guidance and the broader public health debate about diet drinks.
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