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News
Diet drinks hold their own against water for weight loss. A landmark two-year randomized trial of 493 adults found that people who drank diet beverages lost about as much weight as those who drank water — and both groups kept the weight off. The findings push back on concerns that artificial sweeteners disrupt appetite or metabolism.
Diet drinks hold their own against water for weight loss
The longest randomized controlled trial to date on diet beverages has a clear verdict: they work just as well as water for long-term weight management. The SWITCH trial, conducted at the University of Liverpool, enrolled 493 adults with a BMI of 27–35 in a structured behavioral weight loss program. Participants were randomly assigned to drink either water or commercially available diet beverages (sweetened with aspartame, acesulfame-K, or sucralose) for 104 weeks. Both groups lost meaningful weight and kept it off — even through a final year with no program support.
Crucially, the study found no clinically meaningful differences in appetite, blood pressure, or cholesterol between the two groups, pushing back on long-standing concerns that artificial sweeteners interfere with metabolism or hunger regulation. The findings are also timely: the WHO has previously advised against non-sugar sweeteners for weight control, citing uncertainty in observational data — this trial offers rigorous, long-term randomized evidence to challenge that stance.
By the numbers:
Why it matters: For clinicians counseling patients on weight management, this trial offers reassurance that diet beverages are a legitimate alternative to water — not a metabolic trap. It also adds important evidence to global policy conversations about sweetener safety and dietary guidance.
