A new study published in Food Quality and Safety on May 20, 2026, reveals that hunger amplifies the immediate liking and physiological arousal triggered by sweetness itself, not specifically by the calories it provides. The research, conducted by scientists from Jiangnan University in China and the University of Oxford in the United Kingdom, also shows that people who regularly consume non-nutritive sweeteners (NNS) exhibit heightened activity in the left dorsolateral prefrontal cortex (DLPFC), a brain region linked to self-control, when tasting sweet solutions. This suggests that habitual use of zero-calorie sweeteners may strengthen top-down cognitive regulation during eating.
Excessive sugar intake is a major driver of obesity, type 2 diabetes, and cardiovascular disease. In response, non-nutritive sweeteners have become widely used as low-calorie alternatives. However, concerns have grown that chronic NNS consumption might decouple sweet taste from metabolic energy signaling, potentially reshaping taste preferences and reward pathways. Long-term trials have produced conflicting results, with some studies showing shifts in sweet preference and others finding no change. This study directly compared habitual sugar consumers and habitual NNS consumers, measuring their responses to sweetness-matched solutions under both hungry and satiated conditions.
Using a combination of subjective ratings, emotional assessments, electrocardiogram (ECG), and functional near-infrared spectroscopy (fNIRS), the team uncovered a dissociation between what people say they like and how their brains and bodies respond. Participants consistently rated all sweet solutions as more enjoyable when hungry, regardless of whether those solutions contained sugar or only NNS. This hunger-driven boost in liking was accompanied by clear physiological signs of sympathetic nervous system arousal, including significantly shortened R-R intervals and increased heart rate. Contrary to the team's initial hypothesis, hunger did not selectively favor caloric sugar over non-caloric sweetness. In other words, the craving for energy made sweetness itself more appealing, not the calories behind it.
More strikingly, habitual NNS consumers showed a distinct neural signature. While their self-reported liking and emotional responses did not differ from sugar consumers, fNIRS revealed significantly stronger oxygenated hemoglobin responses in their left DLPFC. This neural difference emerged even though all samples were tasted blindly and matched perfectly for sweetness intensity, ruling out simple perceptual explanations. Notably, the emotion analysis involved a relatively small sample of 15 participants per group, so those findings should be interpreted with caution.
The findings suggest that long-term use of NNS may be associated with enhanced prefrontal surveillance during sweet taste processing, potentially reflecting a learned cognitive strategy to manage the hedonic appeal of sweet foods. The authors stated, "Hunger seems to turn up the volume on sweetness itself, making it more appealing whether it comes with calories or not. That was a surprise — we expected hungry people to reach specifically for sugar. But we also saw that habitual NNS users showed a stronger brain response in a region linked to self-control. It is as if their brains are working a little harder to keep their sweet intake in check. This doesn't prove that zero-calorie sweeteners are good or bad, but it does suggest they are not simply neutral — they may change how our brains handle sweet tastes over time."
These findings offer practical guidance for public health and the food industry. Because hunger enhances the appeal of any sweet taste, replacing sugar with NNS in snacks consumed between meals might still satisfy cravings without adding calories. The heightened brain activity in habitual NNS users raises the possibility that these sweeteners could help reinforce cognitive control over food choices, though this remains to be tested. For now, the study suggests that sweetness itself — not just its energy content — powerfully drives hunger-related eating behavior. Reformulating products to be less sweet overall, while ensuring they are still pleasurable, may be a more effective long-term strategy than simply swapping sugar for zero-calorie alternatives. The study was funded by the National Key Research and Development Program of China and the Collaborative Innovation Center of Food Safety and Quality Control in Jiangsu Province.
