Researchers have revealed, for the first time, how artificial sweeteners can stimulate appetite in the brain.
Studies in both animals and people have suggested that consuming artificial sweeteners can make you feel hungry and actually eat more. Now, a comprehensive new study has revealed i88iwhy this response occurs. The results shed light on the effects of artificial sweeteners on the brain in regulating appetite and in altering taste perceptions.
The researchers, from the University of Sydney, identified a new system in the brain that senses and integrates the sweetness and energy (calorie) content of food.
After chronic exposure to a diet that contained the artificial sweetener sucralose, they saw that animals began eating a lot more. The researchers determined that inside the brain's reward centres, sweet sensation is integrated with calorie content. When sweetness versus calories is out of balance for a period of time (e.g. the brains senses sweet but not calories), the brain recalibrates and increases calorie consumption.
Animals fed sucralose consume more food than when fed sugar-sweetened diet
In the study, fruit flies that were exposed to a diet laced with artificial sweetener for prolonged periods (more than five days) were found to consume 30 percent more calories when they were then given naturally sweetened food.
When the scientists investigated why animals were eating more even though they had enough calories, they found that chronic consumption of sucralose actually increased the sweet intensity of real sugar, and this, in turn, increased the animal's overall motivation to eat more food.
This is the first study to identify how artificial sweeteners can stimulate appetite, with researchers identifying a complex neuronal network that responds to artificially sweetened food by telling the animal it hasn't eaten enough calories.
The researchers also found artificial sweeteners promoted hyperactivity, insomnia and decreased sleep quality -- behaviours consistent with a mild starvation or fasting state.
When the researchers replicated this study using mice, they found that, again, the mice that consumed a sucralose-sweetened diet for seven days displayed a significant increase in food intake, and the neuronal pathway involved was the same as in the fruit flies.
Artificial sweeteners not inert
These findings provide further evidence to support the notion that artificially-sweetened foods and drinks may not be as inert as we anticipated. Artificial sweeteners can actually change how animals perceive the sweetness of their food, prompting an increase in caloric consumption.
Source: Cell Metabolism, July 12, 2016.
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