For the first time, a study details how artificial sweeteners make people feel hungry and cause them to eat more. The findings shed new light on how fake sugars affect the brain.
Past research conducted in animal and human subjects suggested that artificial sweeteners actually trigger more cravings. The new findings provide new information on how these sugars affect the brain's appetite regulation and taste perception.
A research team from the Garvan Institute of Medical Research and the Charles Perkins Centre at the University of Sydney found a new brain system that is able to detect and mix both the food's energy content and sweetness level.
According to the study's lead researcher, Greg Neely, an associate professor from the University's Faculty of Science, they found that animals started eating more after a "chronic exposure" to a diet composed of sucralose, an artificial sweetener.
The researchers used fruit flies in the study. For more than five days, they subjected the flies to a diet that contained artificial sweetener. The flies ended up consuming 30 percent more calories compared to when they were exposed to food that was naturally sweetened.
The investigation found that inside the brain's "reward centers," the food's energy content and sweet sensation are integrated.
"When sweetness versus energy is out of balance for a period of time, the brain recalibrates and increases total calories consumed," said Neely.
This means that chronic exposure to artificial sweeteners increases real, nutritious sugar's sweetness intensity, which then causes the animal's motivation to eat more. The new study also found that artificial sweeteners resulted in poorer quality of sleep, insomnia and hyperactivity.
Professor Herbert Herzog from the Garvan Institute of Medical Research, who was part of the research team, said that the study findings support the idea that the sugar-free versions of processed foods and beverages may not be as "inert" as expected. Herzog added that these artificial sweeteners actually alter the way animals perceive the food's sweetness.
"Using this response to artificially sweetened diets, we were able to functionally map a new neuronal network that balances food's palatability with energy content," added Neely. The brain's pathway the team discovered is part of the "conserved starvation response," which makes healthy food taste way better when a person is actually hungry.
Further research is needed to determine if the new study results are applicable to other forms of sweeteners existing today. The new research was published in the Cell Metabolism journal on July 12.