Your Brain Isn't Fooled by Diet Sweeteners

You may try to kid yourself, but your brain won’t fall for it. (Photo: Getty Images)

Diet cookies sound like a dream. You get all the perks of eating sweets without the added calories and fat. But while you can tell yourself they’re just as good as the real thing, new research suggests that your brain isn’t fooled at all.

A study published in the journal Neuron found that certain hormones are released to the gut and brain when we have real sugar. But those same hormones aren’t released when we have artificial sweeteners, which could help explain why you can polish off a bag of fat-free cookies and still feel hungry.

For their research, scientists deprived fruit flies of food for several hours and then gave them the option of having artificial sweeteners (with no nutrients) or real sugar. When the flies licked the sugar, it activated a group of neurons that released a digestion-fueling hormone with receptors in the gut and brain.

Flies that licked the artificial sweetener never had that hormonal reaction, and ended up moving on to lick the regular sugar option to feel full after they ate.

What’s the fruit fly-human connection? We share a lot of the same genes with them, says study co-author Monica Dus, PhD, an assistant professor at the University of Michigan. “A lot of the organs that make up the metabolic pathways in humans and flies are also similar,” she tells Yahoo Health.

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Dus points out that she and her team purposefully made the fake sugar sweeter and better-tasting than the real sugar but the hungry flies still preferred the real stuff, which contained more calories.

So, does this mean that it’s better to go for “real” cookies over ones that contain artificial sweeteners? Maybe, says Beth Warren, a New York-based registered dietitian and the author of Living a Real Life With Real Food, and it’s not just because of the fullness factor.

“Artificial sweeteners are just that — fake,” she tells Yahoo Health. “They are linked with eventual weight gain and although the evidence is not conclusive, may be linked to other forms of cancer.”

Warren adds that not all non-sugar sweeteners are created equal, noting that natural, non-caloric alternatives like Stevia or monk fruit extracts are often better than other non-sugar options.

But while you might feel more satisfied after eating something that contains real sugar, Warren says there’s still danger in having too much of it, since both sugar and artificial sweetener both cause a feeling of pleasure in your brain that makes you want more.

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There are also larger health risks associated with eating too much sugar. A 15-year study published last year in the journal JAMA Internal Medicine found that eating too much sugar increases your risk of dying from heart disease. A review published in the journal Open Heart last year also suggested that sugar is just as bad as salt in impacting a person’s risk of developing hypertension.

Of course, most of us like sweets and you don’t need to avoid them altogether, Warren says. Her advice: Take a pass on the fat-free versions. Not only do they contain artificial sweeteners, they are packed with other ingredients to try to mimic the same taste and texture of the real stuff. “Usually that means tons of artificial chemicals,” says Warren.

While Dus says that it’s still better to avoid sweets when you can, if you’re going to indulge, reach for the real stuff: “Although your mouth feels the taste of sugar when you eat something that is diet, your brain knows it doesn’t have the calories it needs.”

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