Rather than helping people lose weight as they claim, they force people to gorge on sugary snacks later in the day.
Researchers have found that low- calorie foods laced with artificial sweeteners cannot fool the brain, especially when a person is hungry or tired.
Professor Ivan de Araujo, who led the study at Yale University School of Medicine in the US, said: “The consumption of high-calorie beverages is a major contributor to weight gain and obesity, even after the introduction of artificial sweeteners to the market.
“We believe that the discovery is important because it shows how physiological states may impact on our choices between sugars and sweeteners.”
The study, published in The Journal of Physiology, suggests it is hard to fool the brain by providing it with “energyless” sweet flavours. Our pleasure from consuming sweet solutions is driven by the amount of energy it provides.
The consumption of high-calorie beverages is a major contributor to weight gain and obesity
This means that the greater reward received in the brain comes from sugars not artificial sweeteners.
The study in mice identified a specific brain signal critical for determining choice between sugars and sweeteners.
This signal regulates dopamine levels – a chemical necessary for reward signalling in the brain. But this only happens when sugar is broken down into a form where it is usable as fuel for cells of the body to function.
Prof de Araujo added: “According to the data, when we apply substances that interfere with a critical step of the ‘sugar-to-energy pathway’, the interest of the animals in consuming artificial sweetener decreases significantly, along with reductions in brain dopamine levels.
“This is verified by the fact that when hungry mice are given a choice between artificial sweeteners and sugars, they are more likely to completely switch their preferences towards sugars even if the artificial sweetener is much sweeter than the sugar solution.”