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You Cannot Fake Out Your Brain with Artificial Sweeteners


Switching to a diet soda from one loaded in sugar can certainly be a positive step in reducing the amount of calories you consume in a day. But unfortunately, your body knows the difference between artificial sweeteners and the “real stuff.”

Dr. Nicholas Gant from the Sport and Exercise Science department at the University of Auckland’s Centre for Brain Research says “The mouth is a more capable sensory organ than we currently appreciate, able to distinguish carbohydrates from artificial sweeteners when both taste identical.”

The brain knows the difference too: “Carbohydrates are extremely powerful stimuli that have profound and immediate effects on the brain and the systems it controls,” he adds.

Dr. Gant and a team of researchers used functional MRI to look at the effects of three different mouth rinses used before completing an exercise task in 10 study subjects. One solution was sweet and contained carbs, the second sweet but with artificial sweeteners added, and a third that was neither sweet nor contained any carbohydrates. The participants did not even have to swallow the solution for the brain to be activated by the taste.

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The sweet carbohydrate solution activated an area in the brain associated with sensation and muscle performance. It also produced greater activation in regions that control vision and in those associated with reward.

The researchers call this a “sixth sense” – meaning that our bodies are able to detect carbohydrate in the mouth as a separate sense from sweetness. “It’s becoming evident that the brain knows far more about the foods we ingest than just our perception of taste,” says Dr. Gant.

This sixth sense could explain why athletes respond immediately to carbs, Gant’s team writes in the journal Appetite. Past studies have shown that swishing a carbohydrate solution in the mouth and spitting it out improves performance during strenuous exercise.

It’s also been suggested, Gant pointed out, that a failure in signaling between the mouth and the brain is part of the problem in some eating disorders that cause frantic eating behavior. Therefore, understanding this process could also be a key to curing certain eating disorders.

Journal Reference:
Clare E. Turnera, Winston D. Byblowb, Cathy M. Stinearc and Nicholas Gant.Carbohydrate in the mouth enhances activation of brain circuitry involved in motor performance and sensory perception. Appetite,Volume 80, 1 September 2014, Pages 212–219.