Sucralose, a calorie-free artificial sweetener widely used in diet products, may actually stimulate appetite, a growing body of research suggests. On the 27th (local time), foreign media outlet Health examined how sucralose affects appetite and metabolic health.
Sucralose is a zero-calorie sweetener made by chemically modifying sugar molecules. About 600 times sweeter than sugar yet virtually calorie-free, it is widely used in zero-calorie sodas, sugar-free desserts and low-calorie snacks. Consumers who need to manage their weight or blood sugar often reach for it instead of sugar, and sucralose is also the main ingredient in Splenda, a sugar substitute commonly seen at cafes.
The problem is that when the human body detects sweetness, it responds as if a corresponding amount of calories will follow. Because sucralose delivers strong sweetness with almost no calories, repeated mismatches between taste and energy intake can lead the brain to conclude that sufficient energy has not been supplied, switching on appetite signals. This is cited as a reason why hunger quickly returns even after drinking a zero-calorie beverage.
Imaging studies have confirmed this mechanism. Researchers at the Keck School of Medicine of the University of Southern California (USC) had 75 adults drink water, sugar water and a sucralose beverage, and scanned their brains using functional magnetic resonance imaging (fMRI). Sucralose boosted activity in the hypothalamus, which regulates appetite and body weight, more than sugar did. Connectivity with motivation and sensory processing regions also increased. The effect was most pronounced in the obese group. The study was published in March in the international journal Nature Metabolism.
Long-term tracking data shows a similar pattern. Researchers at the University of Manitoba in Canada analyzed cohort data from about 400,000 adults and found that the group that consistently consumed artificial sweeteners tended to gain more in weight, waist circumference and body mass index (BMI). The researchers said in the Canadian Medical Association Journal (CMAJ) that they confirmed long-term consumption of artificial sweeteners is linked to the risk of obesity and type 2 diabetes. The World Health Organization (WHO) in 2023 also issued a guideline advising against the use of non-sugar sweeteners for dieting, stating that "non-sugar sweeteners do not help with long-term weight control."
The U.S. Food and Drug Administration (FDA) still classifies sucralose as a safe substance. Its acceptable daily intake (ADI) is 5 mg per kilogram of body weight. However, replacing sugar with artificial sweeteners does not eliminate the dietary habit of craving sweetness itself. That is why zero calories alone cannot be considered a healthy choice.
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