A new study led by USC reveals that sucralose, a common calorie-free sweetener, disrupts brain signals that regulate appetite, particularly in individuals with obesity. This discovery questions the effectiveness of sugar substitutes in weight management and highlights their potential long-term effects on eating behaviors.
A recent study led by researchers at the University of Southern California (USC) uncovers that sucralose, a popular calorie-free sweetener, significantly alters brain activity related to hunger and cravings. Published in Nature Metabolism, the findings are especially concerning given that around 40% of Americans regularly consume sugar substitutes.
“But are these substances actually helpful for regulating body weight? What happens in the body and brain when we consume [them], and do the effects differ from one person to the next?” corresponding author Kathleen Alanna Page, director of the USC Diabetes and Obesity Research Institute and co-chief of the Division of Endocrinology and Diabetes at the Keck School of Medicine of USC, said in a news release.
Study Highlights Unexpected Brain Responses
Page and her team conducted a randomized experiment with 75 participants, exploring how sucralose influences brain activity, hormone levels and hunger.
The participants were tested with water, sucralose-sweetened drinks and sugar-sweetened drinks over three separate visits, utilizing functional magnetic resonance imaging (fMRI) brain scans, blood samples and hunger ratings.
The study revealed that, compared to sugar, sucralose heightened activity in the hypothalamus — a crucial brain area involved in appetite regulation — and this effect was prominent in individuals with obesity. Also, unlike sugar, sucralose did not elevate blood levels of hormones that signal fullness, such as insulin and GLP-1.
“The body uses these hormones to tell the brain you’ve consumed calories, in order to decrease hunger. Sucralose did not have that effect — and the differences in hormone responses to sucralose compared to sugar were even more pronounced in participants with obesity,” Page added.
Implications for Weight Management
Previous studies hinted that calorie-free sweeteners might be linked to obesity, mostly based on animal models and large-scale population data. However, this USC study provides direct evidence of how these substances impact human brain and body responses.
The mismatch between the sweet taste of sucralose and the absence of caloric energy appears to confuse the brain’s appetite signals, potentially affecting long-term eating behavior.
“If your body is expecting a calorie because of the sweetness, but doesn’t get the calorie it’s expecting, that could change the way the brain is primed to crave those substances over time,” added Page, who is also an associate professor of medicine at the Keck School of Medicine.
Future Research Directions
The study also found that female participants experienced greater changes in brain activity than males, indicating sex-specific responses to sucralose. These findings necessitate further investigation into how different demographics are affected by calorie-free sweeteners.
Page and her team are now focusing on the impact of such sweeteners on children and adolescents, the age group that consumes the most sugar and sugar substitutes.
“Are these substances leading to changes in the developing brains of children who are at risk for obesity? The brain is vulnerable during this time, so it could be a critical opportunity to intervene,” Page added.
As sugar substitutes become more prevalent, understanding their comprehensive impact on the human brain and body ensures better dietary recommendations and public health strategies. This research underscores the complexity of nutrition science and the need for thorough investigation into seemingly beneficial alternatives, such as calorie-free sweeteners.
Source: Keck School of Medicine of USC