Why Diet Soda Will Never Top the Real Thing
"The diet soda business is in freefall." For three straight years, sales of low-calorie sodas have slipped. While there are many reasons for the decline, there's one glaring contribution: Diet soda is not as addictive as the real thing.
To our brains, the difference between soda and diet soda is as clear as day. When carbonated sugar water rushes down our gullets and is eventually digested, the sugar molecules contained within are recognized by dopamine receptors in the brain. It's a signal that they should execute their one and only duty: to release dopamine. And so, the hormone synonymous with reward and pleasure pours out in a torrent, prompting a cascade of good feelings and a desire for one thing: more dopamine. That's usually when we crack open another can of soda.
None of this happens with diet soda. While just as sweet as normal soda and similar in taste, diet soda utilizes artificial sweeteners: often sucralose or aspartame. The brain's dopamine receptors aren't fooled by the deceit, and so stay silent.
More often than not, we don't eat because we're physically hungry. We eat because food gives us pleasure. This fact is mirrored in mouse studies. In 2011, researchers used light techniques to activate the animals' dopamine receptors as they drank water. Even though the water wasn't sweet at all, the mice gulped it down in huge amounts. Later on, when they were offered both water and sugar, the mice preferred water.
The term "sugar addiction" is not a media-spawned overstatement; it's real.
"The repeated consumption of high levels of sucrose can create a cycle of continued overconsumption -- even compulsive eating -- in order to recapture the initial feelings of pleasure," Cristina García-Cáceres and Matthias H Tschöp, both researchers at the Helmholtz Diabetes Center in Germany, recently wrote. "This is similar in many ways to drug abuse or addiction, and also involves some of the same signaling pathways within the body."
A can of full calorie soda contains at least 35 grams of sugar in some form -- often either sucrose or high-fructose corn syrup. Diet soda has none.
It's simply not a fair fight.