Sugar is the dietary downfall of a lot of people. And a lot of studies in recent years have looked at the ways in which food -- especially sugar -- actually functions like an addiction in the brain.

As Yale researchers point out in a new  study, sugar's "siren song" is particularly hard to resist, since our brains respond to it in multiple ways. The team has made an interesting discovery about how the brain processes sugar, teasing apart whether it's reacting more to the flavor or the energy it provides.

The researchers studied mice to answer this question. They offered them two different foods -- a sugar-flavored food that was devoid of calories, and another that tasted terrible, but had the calorie content of sugar. Then they looked at what was happening in the mice's brains: Different regions of the brain's striatum (a primitive area involved in reward) "lit up" in response to the respective foods, suggesting that the brain processes flavor vs. energy content separately. 

When offered both, the mice also preferred the high-energy (but terrible-tasting) food over the one that tasted good but provided no nutrition.

"The sugar-responsive circuitry in the brain is therefore hardwired to prioritize calorie-seeking over taste quality," said study author Ivan de Araujo. "Highly palatable yet non-nutritive stimuli carry a much weaker reward value to an organism compared to less palatable and yet caloric ones."

In other words, the brain has two different circuits for processing the two different elements of food, and when pitted against each other, calorie content seems to win out over energy content. Luckily, in real life, the brain rarely has to choose between the two -- sweetness is usually an extremely accurate predictor of calories.

But the study helps explain why when we try to hack the system -- by developing things like sugar substitutes--it doesn't really work. Artificial sweeteners haven't really changed our collective sugar intake, or been shown to help much with weight gain, says de Araujo, possibly because the brain or body is compensating for the alien combination of sweetness without energy.

And if you're wondering, the study results likely apply to humans too: When it comes to food craving and reward, our brain circuits are surprisingly similar to those of mice. Of course, our relationship with food may be a little more complex, since there's an obvious emotional element to our eating patterns, not to mention at least the notion of self-control. And both of these can influence our choices.

Keeping in mind studies like this may help us be more aware of the choices we make - when we're mindlessly reaching for a bag of gummy bears or a soda as a pick-me-up, it may be helpful to think about the ancient cells in your brain that are making you do this. And if possible, redirecting to a snack that will provide a slower, steadier rise in blood sugar than the quick spike-and-fall of sugar. Your brain may crave sugar, but that doesn't mean you have to listen to it every time.