Sucralose’s role in dieting is being reconsidered after a recent study from the University of Southern California found it may do the opposite of what’s intended. The research, which used MRI to study brain activity, continues to raise red flags about the sweetener’s impact on appetite.
How Artificial Sweeteners Affect the Body and Brain
Non-caloric sweeteners like sucralose have become mainstays of modern diets, showing up in everything from fizzy drinks to baked goods. A recent study focused on the brain’s hypothalamus to examine how it responds to sucralose in comparison with sugar and water. Sucralose, known commercially as Splenda, can be up to 650 times sweeter than sucrose by weight.
Tracking Brain Responses to Sweeteners
Seventy-five young adults took part in a controlled study designed to map how the brain processes different sweeteners.
Divided by body weight into healthy, overweight, and obese groups, participants consumed sucralose, sucrose, or water across three sessions. MRI scans, taken before and after intake, focused on changes in the hypothalamus—an area central to hunger regulation—while participants reported how hungry they felt at each time point.
Sucralose Increases Hunger-Related Brain Activity
The study revealed that sucralose significantly increased blood flow in the hypothalamus compared to both sucrose and water, indicating a heightened hunger response. Additionally, functional MRI analysis showed that sucralose “significantly increased coupling between the hypothalamus and the anterior cingulate cortex”—a brain region involved in reward and cravings.
This discovery could explain why people sometimes report feeling hungrier after consuming diet products. The brain may process the sweet taste as a cue for incoming calories, and when those calories never arrive, it could amplify cravings instead of satisfying them.
Hunger Responses Varied by Weight and Gender
MRI data revealed that sucralose led to a pronounced rise in hypothalamic blood flow, signalling a greater hunger response than sucrose or water.
Researchers also observed that sucralose “significantly increased coupling between the hypothalamus and the anterior cingulate cortex,” a brain region involved in cravings and reward. The findings point to a possible mismatch between perceived sweetness and actual caloric intake.
Hunger Ratings Mirror Brain Findings
Participants self-reported feeling hungrier after drinking sucralose-sweetened beverages than after drinking sucrose, in addition to MRI results. There was no significant difference in hunger levels compared to water, which researchers believe is due to sucralose’s inability to trigger satiety hormones.
“The participants felt hungrier after consuming sucralose versus sugar,” the study noted. “The researchers believe that sucralose does not trigger hormones that tell the body it is full.”
Experts Call for Caution on Non-Caloric Sweeteners
Self-reported hunger levels rose after participants consumed sucralose, surpassing those recorded after sugar intake. However, no significant difference emerged between sucralose and water, suggesting the artificial sweetener may not stimulate the body’s fullness signals.
“The participants felt hungrier after consuming sucralose versus sugar,” the study noted. “The researchers believe that sucralose does not trigger hormones that tell the body it is full.”
Conclusion
Promoted for decades as a calorie-free solution for managing weight, artificial sweeteners are now facing renewed questions. The study’s results suggest sucralose could stimulate appetite rather than suppress it, especially in certain populations.
While researchers caution that more work is needed, the findings could influence future nutritional recommendations in an era of increasingly tailored dietary advice.