Brain can detect calorie content even when one doesn't taste the food, new study seems to suggest.
Researchers at the Duke University Center in Durham, North Carolina first genetically altered the brains of mice, making them unable to taste "sweet."
They then had the sweet-blind mice undergo tests in which they were given a choice of a sugar solution and one sweetened with the non-caloric sweetener sucralose.
They found the mice showed a decided preference for the higher-calorie sugar solution — indicating that the calorie content — not the taste — likely governed their decision.
The researchers also discovered that the reward response in the brains of the mice triggered the release of dopamine, a brain chemical associated with pleasure.
The preference for the sugar developed after ten minutes of an hour-long feeding session, they found.
The study shows that even in the absence of taste, physiologic changes in the body let the brain know a high-calorie food has been ingested. "Our findings suggest that calorie-rich nutrients can directly influence brain reward circuits that control food intake independently of palatability or functional taste transduction," the authors write.
They say this finding could change how obesity is tackled, viewing the consumption of foods as a process that is driven not only by taste but also by caloric training of the brain.
This means that if a person is dieting and consuming lower-calorie foods, the body will still sense that it isn't getting enough calories.
The study is published in the March 27 issue of the journal Neuron.