Diet soft drinks may be tricking your brain into thinking you're hungry when you're not, according to a new study.
Researchers from the University of California and San Diego State University found that artificial sweeteners — such as saccharin — used as sugar substitutes in diet drinks may lead to excessive eating because of the chemical reactions they can cause in the brain.
Using brain imaging technology, scientists Erin Green and Claire Murphy found that a person who regularly consumes sweet flavours processes them differently to a person who does not. So when a sweetener like saccharin is introduced into the body of someone who is not a regular consumer of sweet foods, the brain becomes disoriented and cannot distinguish between artificial and regular sugar.
This contradicts previous studies which have demonstrated that the brain is able to tell the difference between real and substitute sugar.
In response to the claims, Susan Swithers of Purdue University told ScienceNews.org: "This idea that there could be fundamental differences in how people respond to sweet tastes based on their experience with diet sodas is not something that has gotten much attention."
The study used 24 young adults — half of whom reported regularly drinking diet soft drinks and half who said they rarely consumed them — to achieve its results. The test subjects were given small doses of water, some sweetened with sugar and some with saccharin, and were asked to grade the taste of what they were given.
The results of the scans, which will be published in the journal Physiology & Behaviour, showed that the area of the brain associated with food deprivation "lit up" in those who frequently drank fizzy beverages when they consumed the water with saccharin.
"The brain normally uses a learned relationship between sweet taste and the delivery of calories to help it regulate food intake", conceded Swithers. However when extra calories are suddenly delivered by a sweet food, the brain "suddenly has no idea what to expect".
As the body's food regulator, it then becomes habit for the brain to ignore sweet sensations when it assesses how many calories are being delivered by a food or drink.
So it's worth proceeding with caution if trying a new diet with diet soft drinks on the menu.