A study published in Food Quality and Safety reveals that hunger amplifies the immediate appeal of sweet taste, regardless of whether the sweetness comes from sugar or non-nutritive sweeteners (NNS). The research, conducted by scientists from Jiangnan University in China and the University of Oxford, also found that people who regularly consume NNS exhibit heightened activity in the left dorsolateral prefrontal cortex (DLPFC), a brain region associated with cognitive control and self-regulation.
The study directly compared habitual sugar consumers and habitual NNS consumers, measuring their responses to 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 neural responses.
Participants consistently rated all sweet solutions as more enjoyable when hungry, regardless of caloric content. This hunger-driven boost was accompanied by physiological signs of sympathetic arousal, including shortened R-R intervals (RR-I) and increased heart rate (HR). Contrary to the initial hypothesis, hunger did not selectively favor caloric sugar over non-caloric sweetness. "Hunger seems to turn up the volume on sweetness itself, making it more appealing whether it comes with calories or not," the authors noted.
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 (O₂Hb) responses in their left DLPFC. This neural difference emerged even though all samples were tasted blindly and matched for sweetness intensity. The authors suggest that long-term NNS use may be associated with enhanced prefrontal surveillance during sweet taste processing, potentially reflecting a learned cognitive strategy to manage hedonic appeal.
These findings have practical implications 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. The study suggests that sweetness itself—not just its energy content—powerfully drives hunger-related eating behavior, and reformulating products to be less sweet overall may be a more effective long-term strategy than simply swapping sugar for zero-calorie alternatives.
The study is published in Food Quality and Safety (DOI: 10.1093/fqsafe/fyag046). Funding was provided by the National Key Research and Development Program of China and the Collaborative Innovation Center of Food Safety and Quality Control in Jiangsu Province.
