Sugar substitutes fail to fuel sweet cravings or weight gain across yearlong trials

by Institute for the Advancement of Food & Nutrition Sciences

edited by Lisa Lock, reviewed by Robert Egan

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A newly published narrative review in the journal Nutrients brings together findings from three large European research consortia—SWEET, SWITCH and Sweet Tooth—to address longstanding questions about whether non-nutritive sweeteners (NNSs) and sweet-tasting foods in general affect body weight, metabolic health and people's taste preferences over time.

The review, led by Eva Marija Čad of the University of Ljubljana and Wageningen University & Research, alongside colleagues from the University of Leeds and other institutions in the Netherlands, Denmark, Spain and Belgium, was developed in connection with a 2025 webinar series hosted by the Institute for the Advancement of Food and Nutrition Sciences (IAFNS).

Public health guidance on sugar substitutes has been inconsistent. Some bodies, including the World Health Organization, have cautioned against relying on non-nutritive sweeteners for weight control and have suggested reducing sweetness in the diet overall—regardless of its source.

Other professional groups, including several in the U.K., view NNSs as a legitimate tool for cutting sugar intake. Much of the disagreement traces back to a divide between randomized controlled trials, which tend to show neutral or favorable effects, and observational studies, which more often report associations with health risks—associations that can be distorted by the fact that people already at higher metabolic risk tend to consume more sweeteners in the first place.

To help resolve some of this uncertainty, the authors focused specifically on evidence from three large European multi-year, multicenter randomized trials designed to isolate cause-and-effect relationships under real-world conditions.

Findings

Weight and body composition: Across all three consortia, replacing sugar with non-nutritive sweeteners did not undermine weight loss or maintenance—and in some cases appeared to help. In a one-year weight-loss-maintenance trial from the SWEET consortium, participants who included NNSs in their diet maintained modestly greater weight loss after a year than those who avoided them, with the largest differences seen among the most adherent participants.

A separate 52-week SWITCH trial found that people drinking NNS-sweetened beverages lost slightly more weight than those drinking water, though the difference fell short of a threshold considered clinically meaningful. Meanwhile, the Sweet Tooth trial, which manipulated overall dietary sweetness exposure up or down without any weight-loss goal, found no meaningful impact on body weight or body composition either way.

Metabolic and cardiovascular markers: Blood sugar, insulin, blood pressure, cholesterol, liver enzymes and related biomarkers were generally stable and comparable across sweetener and nonsweetener groups. In some acute and short-term tests, replacing sugar with sweeteners was linked to smaller post-meal blood sugar and insulin spikes. A modest shift in gut bacteria composition was observed in one sub-study, but it wasn't accompanied by any worsening of cardiometabolic risk markers.

Sweet taste preference and appetite: The review found no support for the idea that consuming sweeteners—or a sweeter diet generally—trains people to crave more sweetness or eat more overall. In fact, in the SWEET weight-maintenance trial, people who avoided sweeteners actually developed a stronger liking for sweet foods over time, while those who used sweeteners did not. Across the trials, measures of hunger, cravings and actual food intake were largely similar regardless of sweetener use or sweetness exposure level.

Caveats

The authors note important limits to the evidence. The trials were conducted mainly in overweight adults, often within structured behavioral or clinical programs, so results may not generalize to other populations or everyday eating patterns. Some outcomes were secondary or exploratory, dropout rates were higher than ideal in places, and self-reported dietary intake is prone to underreporting. The authors emphasize that null findings reflect no detectable difference within the specific populations and timeframes studied—not proof that no effect exists under any circumstances. Long-term effects, and effects in children and adolescents, remain unclear.

Bottom line

Taken together, the SWEET, SWITCH and Sweet Tooth consortia offer some of the most rigorous experimental evidence to date on this topic. The findings suggest that swapping sugar for non-nutritive sweeteners can be a useful tool in weight management strategies without apparent harm to metabolic health and that broader differences in how sweet a person's diet is do not appear to meaningfully affect body weight, biomarkers or taste preferences over the periods studied.

According to Eva Marija Cad at the University of Ljubljana, "The findings from all three major European consortia point in the same direction and add important weight to the broader evidence on non-nutritive sweeteners and sweet taste. Collectively, they suggest that we can reduce sugar intake while retaining sweetness and the enjoyment it brings in our diets."

According to Graham Finlayson at the University of Leeds, "A common concern is that replacing sugar with non-nutritive sweeteners might lead to a stronger preference for sugary sweet foods or stimulate appetite. Across these controlled studies, that prediction was not supported. Sweeteners are not a weight-management strategy by themselves, but they can provide a useful way to reduce sugar while retaining sweetness within a broader healthy diet."

Publication details

Eva Marija Čad et al, Effects of Non-Nutritive Sweeteners and Sweet Taste Exposure on Weight Management, Biomarkers of Health and Sweet Taste Preference—A Review of the Evidence from Recent European Consortia Studies, Nutrients (2026). DOI: 10.3390/nu18111647

Journal information: Nutrients

Key medical concepts

Non-Nutritive SweetenersBody Weight

Clinical categories

Nutrition & Healthy eatingWeight managementEndocrinologyHealthy living Provided by Institute for the Advancement of Food & Nutrition Sciences Who's behind this story?

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