Fake Sugar Can't Fake Out the Brain

May 6, 2008 — -- So you want to indulge in that sugar-coated doughnut because it tastes so sweet? You probably would want it just as much if it didn't taste sweet at all.

Medical researchers at Duke University have found that the brain has a "sixth sense" for finding calories even if the taste for sweets is taken away.

The research, published in a recent issue of the journal Neuron, is the latest in a long list of studies showing just how tricky the brain can be when it comes to shedding those extra pounds.

Even when we think we're doing right, we're often doing exactly the wrong thing, because the brain is an awful thing to waist, if you'll pardon the pun.

For example, an ongoing series of experiments at Purdue University has shown that artificial sweeteners may be so confusing to the brain that they may contribute to weight gain, not weight loss.

Researchers there found that rats given yogurt with zero-calorie saccharin gained more weight, put on more body fat and didn't make up for it by cutting back later, compared to rats given yogurt sweetened with ordinary table sugar.

The study, published in Behavioral Neuroscience, suggests that artificial sweeteners trick the brain into thinking that a truckload of calories will follow soon, thus increasing hunger and contributing to the condition known to medical professionals as "pigging out."

However, some other studies have reached very different conclusions about artificial sweeteners, so more work needs to be done on that one.

The Duke study is one of the more intriguing findings in this very fuzzy arena. Ivan de Araujo and several colleagues experimented with mice that had been robbed of the taste receptor cells that make it possible to detect the taste of sweetness.

These genetically altered "sweet-blind" mice weren't fooled by an artificial sweetener. They knew it didn't have enough calories, according to the researchers, so they selectively dined at a "sipper" that offered high-caloric sugar water while largely ignoring a sipper with a noncaloric sweetener.