Study reveals why sweeteners can make you feel hungry

A new study has revealed, for the first time, why consuming artificial sweeteners can make you feel hungry.

The study, co-led by researchers from the University of Sydney and the Garvan Institute of Medical Research, sheds light on the effects of artificial sweeteners on the brain in regulating appetite and in altering taste perceptions.

In the study, fruit flies that were exposed to a diet laced with artificial sweetener for prolonged periods were found to consume 30% more calories when they were then given naturally sweetened food.

“When we investigated why animals were eating more even though they had enough calories, we found that chronic consumption of this artificial sweetener actually increases the sweet intensity of real nutritive sugar, and this then increases the animal’s overall motivation to eat more food,” said Associate Professor Greg Neely from the University of Sydney’s Faculty of Science.

Changes in the perception of sweetness

The researchers identified a complex neuronal network that responds to artificially sweetened food by telling the animal it hasn’t eaten enough energy.

“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. The pathway we discovered is part of a conserved starvation response that actually makes nutritious food taste better when you are starving,” said Associate Professor Neely.

The researchers also found artificial sweeteners promoted hyperactivity, insomnia and decreased sleep quality with similar effects on sleep also previously reported in human studies.

Professor Herbert Herzog’s lab from Garvan then went on to replicate the study using mice. Mice that consumed a sucralose-sweetened diet for seven days displayed a significant increase in food consumption, and the neuronal pathway involved was the same as in the fruit flies.

“These findings further reinforce the idea that ‘sugar-free’ varieties of processed food and drink may not be as inert as we anticipated. Artificial sweeteners can actually change how animals perceive the sweetness of their food, with a discrepancy between sweetness and energy levels prompting an increase in caloric consumption,” Professor Herzog said.