If you’ve ever wondered why faithfully drinking diet soda every day can seem to cause weight gain instead of desired weight loss, a brain imaging research study from San Diego State & UC San Diego sheds some light on possible causes.
The study looked at brain regions associated with food reward, and noted some important differences between participants who regularly consumed several zero calorie sodas each week, and participants who didn’t drink diet soda as part of their weekly routine.
It turns out that habitual diet soda drinkers had an outsize response in their brains to any sweet taste (both artificial & natural) compared to non-diet soda drinkers. More importantly, the brains of diet soda drinkers had lost the ability to differentiate between “real” sugar and “fake” sugar, compared to the control group.
When Your Brain Can’t Tell The Difference
This result has some startling implications on how artificial sweeteners might be altering the finely tuned reward circuits that drive much of human behavior, especially when it comes to food choices.
The first implication is that artificial sweeteners (saccharin, aspartame, etc) offer up the false promise of a high calorie/high energy food source to our evolutionary ancient mammal brains, but the body ends up getting “cheated” when consumption of very sweet fake sugar doesn’t result in any calorie intake.
A second result is the possibility that if our brains lose the ability to differentiate between sucrose (high calorie/high energy content) and artificial sweeteners (no calorie/no energy content), the brain’s food reward feedback loop will begin to discount the importance and value of any sweet food.
Paradoxically, this may well mean that food intake will actually increase over time, since the brain’s food reward circuits can’t reliably signal the difference between real and artificial sugar choices.
The SDSU/UCSD study supports this possibility with the discussion that the right caudate (a brain region directly involved in feeding behaviors), showed lower activation in habitual diet soda drinkers compared the control group. Lower activation in the right caudate is typically associated with dis-inhibition and compulsive behaviors, such as mindlessly reaching for that third diet soda in the afternoon.
Food for thought, so to speak.
See also– This is Your Brain on Fat and Sugar.