A new study published in Food Quality and Safety reveals that hunger increases the 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 found 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.
The study, published on May 20, 2026 (DOI:10.1093/fqsafe/fyag046), directly compared habitual sugar consumers and habitual NNS consumers. Participants rated sweetness-matched solutions under both hungry and satiated conditions. Using subjective ratings, emotional assessments, electrocardiogram (ECG), and functional near-infrared spectroscopy (fNIRS), the team uncovered a dissociation between self-reported liking and brain responses.
Participants consistently rated all sweet solutions as more enjoyable when hungry, regardless of whether they contained sugar or only NNS. This hunger-driven boost in liking was accompanied by physiological signs of sympathetic nervous system arousal, including shortened R-R intervals and increased heart rate. Contrary to the team's hypothesis, hunger did not selectively favor caloric sugar over non-caloric sweetness. 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 for sweetness intensity, ruling out simple perceptual explanations. The study's CATA emotion analysis involved a relatively small sample of 15 participants per group, so those findings should be interpreted with caution.
"Hunger seems to turn up the volume on sweetness itself, making it more appealing whether it comes with calories or not," the authors said. "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."
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.
