Could diet soda make you fat How zero-calorie sweeteners trick your brain into thinking you're hungry when you're not
17:47 GMT, 19 June 2012
Drinking diet soda could have the exact opposite results when it comes to weight loss than we have been led to believe, according to a new study.
Researchers in San Diego have revealed that low-to-no calorie fizzy beverages could actually encourage overeating and contribute to obesity.
Scientists are attributing the startling new findings to a chemical reaction in the brain when saccharin is introduced to the blood stream of a person who regularly consumes diet drinks versus one who doesn't.
Fattening A new report finds that drinking diet soda could in fact make you eat more and put on weight
At some level, scientists believe, the brain can distinguish between calorie-free sweetener and regular sugar but in those that drink diet soda at least once a day, new tests showed that the brain became confused and could no longer tell the difference.
If this is the case, then calorific intake and subsequent energy consumption cannot be 'calculated' and a person is tricked into thinking they need more food.
Susan Swithers of Purdue University in West Lafayette, Indiana admitted to 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 tests that found these aberrations in 'reward activation' areas of the brain were conducted by Erin Green and Claire Murphy of the University of California, San Diego, and San Diego State University scientists.
24 healthy young adults were subjected to a series of brain imagining tests while being given small doses of saccharin and sugar-sweetened water and asked to rate the tastes.
Half of the participants were frequent consumers of diet soda and half claimed they hardly ever indulged in the fizzy drinks but both reported back with enjoyable experiences of flavour.
'There could be fundamental differences in how people respond to sweet tastes based on their experience with diet sodas'
The scans, however, simultaneously
picked up on the brain's activity while drinking both variations and
found that different 'regions' lit up between the two test groups.
The results, that will be published in an upcoming issue of Physiology & Behavior, showed that as diet soda drinkers consumed the saccharin-sweetened water, the activation of an area that deals with food motivation diminished.
This, as the researchers pointed out, has been linked to an elevated risk of obesity in previous studies.
The Purdue University professor explained: 'The brain normally uses a learned relationship between sweet taste and the delivery of calories to help it regulate food intake' but when a sweet food unreliably delivers bonus calories, the brain 'suddenly has no idea what to expect.'
The result, she concluded, is that the body learns to ignore sweet tastes in its predictions of a food's energy content.