The team studied 99 healthy adults with an average age of 24. Participants were selected because they had similar opinions about sugar and artificial sweeteners. Most reported that they liked both about the same.

But when researchers subtly shifted what participants believed they were drinking, their experience changed. If people were told they were consuming a drink with artificial sweeteners, they rated sugar-containing drinks as less enjoyable. On the other hand, when participants thought a drink contained sugar, they reported greater enjoyment, even when the drink actually used artificial sweeteners.

Brain imaging revealed that these expectations were not just influencing opinions. They also affected activity in a key reward-related region of the brain. When participants believed they were drinking sugar, this area became more active, even if the drink did not actually contain sugar.

Says Westwater, "This could mean that this brain area, the dopaminergic midbrain, processes increased nutrients or calories of sweet flavors, which supports rodent work showing that this brain region is important for sugar seeking."

The results highlight how expectation plays a powerful role in both behavior and brain activity related to sweetness. In other words, what people think they are consuming can shape not only their perception of taste but also how their brain responds to it.

Westwater also pointed to possible real-world applications, especially for improving dietary habits. "If we emphasize that healthier food alternatives are 'nutrient rich,' or have 'minimal added sugars,' this may create more positive expectations than using terms like 'diet' or 'low calories.' This may help people align their food choices with the brain's preference for calories while supporting behavior change."

Although these ideas are not entirely new in clinical settings, the researchers believe the study adds valuable insight. Westwater hopes the findings will influence how scientists approach research on eating behavior and nutrition going forward.