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This question originally appeared on Quora. Answer by Keck Medicine of USC.

We all know what sugar does to our waistlines. New studies show its impact on the brain — and it’s not good.

As it turns out sugar is not so sweet. Besides causing obesity and diabetes, eating a diet saturated with sugar is linked to a number of abnormal brain functions, including poor memory and cognitive activities. Here’s what you need to know to prevent a sugar overload.

Not all sugars are bad.

Our bodies turn most of the food we eat into sugar. Good sugar, or glucose, comes from carbohydrates like bread and pasta. It fuels the cells throughout our bodies, including our brains.

The second type of sugar is fructose. When eaten in fruits and vegetables, fructose is harmless, but when consumed in foods like soft drinks, honey, and virtually any processed foods like condiments, salad dressings, and junk food, fructose can be detrimental to our health. “Fructose fails to stimulate hormones, like insulin, that are important in helping us feel full,” said Kathleen Page, MD, assistant professor of clinical medicine at Keck Medicine of USC.

Sugar is addictive.

It takes only one bite of sugar to stimulate the brain to release dopamine, a natural chemical in the brain that drives our cravings and motivations. It’s the same chemical that also causes alcoholics and drug addicts to constantly seek a “high.” In a USC study, participants who ate foods with fructose compared to glucose experienced increased hunger and cravings.

“We gave volunteers choices between being served tasty food immediately after the study or having money sent to them one month later,” said Dr. Page. “When the study participants consumed fructose, they had a greater willingness to give up the money to obtain immediate high-calorie foods, compared to when they consumed glucose.”

Sugar ages skin.

We can’t blame it all on the sun. Too much sugar breaks down the collagen and elastin in our skin, which keeps the cells from repairing themselves. Even worse, there’s no way to heal the damage once premature wrinkles have formed. The only fix is keeping sugar intake to a minimum or eliminating it altogether.

Sugar numbs our overeating “sensor.”

It’s a common fact that a high-sugar diet makes us fat. But only recently have researchers figured out that chronic consumption numbs the brain’s anorexigenic oxytocin system, the sensor that prevents overeating. When our brain doesn’t release hormones to signal that we’re full, we’re more likely to continue eating.

Sugar reduces our BDNF factor.

Our brain-derived neurotrophic factor (BDNF) assists our brains with learning and forming new memories. When our BDNF level is low, we get stuck, unable to learn new things. Our memory diminishes. Some research has even discovered links between low BDNF factors and Alzheimer’s, depression and dementia.

Sugar withdrawal is real.

Eliminating sugar from our diets can cause the same reactions as withdrawals from drugs — teeth chattering, anxiousness, tremors and head shakes. The first and most important way of breaking free of sugar dependence is a drastic change in diet. “The best way to reduce fructose intake is to decrease the consumption of added sugar sweeteners, the main source of fructose in the American diet,” said Page.

If you’re ready to explore healthier nutritional options, consider meeting with a digestive expert to discuss a personalized plan.

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