We’ve all said it, even if we regret it: “There’s always room for dessert.” Turns out, there is a scientific explanation for why we can consume so many sweets compared to other types of foods with a similar number of calories. For sweets, the threshold for satiety, which is triggered by the human appetite center in the ventromedial hypothalamus, is higher than any other flavor stimulants — meaning we can eat many more sugary foods than salty or savory ones.
Essentially, sugar is a vehicle that makes you able to eat more. And because sugars are added in everything from salad dressings to pasta sauce to bread and other processed foods, people tend to eat more of many things than they normally would — without that sugar throwing their satiety center out of whack, said Dr. D. L. Katz, the founding director of Yale University’s Prevention Research Center.
“Having the sugar there is a pretty reliable way of getting people to eat more of it than they otherwise would, to run out sooner, and to go back to the store and buy more — and if you’re selling the stuff, that’s a great formula,” Katz told Salon in a phone interview. “The result is that sugar is in everything.”
We like sugar so much that we often call foods steeped in it “addictive” or “like crack,” despite this comparison having little to do with substance use disorders. Or is it relevant after all? Is sugar essentially a drug?
While sugar is not classified as a drug in the traditional sense, scientific evidence suggests that its effects on the brain’s reward system and dopamine receptors are similar to those of addictive drugs. Of course, just because something acts on the same receptors does not make it a one-to-one comparison to a drug. For example, nicotine is a drug that interacts with acetylcholine receptors, but so does choline, an essential nutrient that is not considered a drug.
The American Psychiatric Association (APA) defines substance use disorder as a repeated and uncontrollable pattern of substance use that causes impairment or distress. A substance is considered addictive if a person can build up a tolerance to a drug and experiences withdrawal when not using it. Although sugar is not included in the APA’s list of substances, some argue that sugar should be considered a drug, and various countries have moved to restrict its consumption by implementing taxes or changing dietary guidelines.
“[Sugar] seems to be different in that it is acting more like a drug in the brain than it is a food.”
“What we’ve been able to show over the past several years is that, yes, sugar could meet the criteria for being an addictive substance,” said Dr. Nicole Avena, a neuroscience professor at Mount Sinai who recently wrote a book on sugar addiction. “It can produce signs of craving and withdrawal; it can produce alterations in behavior, and people have this kind of loss of control [with sugar] that comes along with substance use disorder in many cases.”
In rodent studies, sugar consumption has been shown to release chemicals in the brain similar to other addictive substances like alcohol or nicotine, including the release of dopamine and endogenous opioids. As a result, eating sugary foods feels pleasurable, encouraging us to do more of it.
“Traditionally, when you’re eating food, it’s not going to release dopamine,” Avena told Salon in a phone interview. “[Sugar] seems to be different in that it is acting more like a drug in the brain than it is a food.”
Interestingly, some studies have shown that people with an allele to the dopamine D2 receptor gene are more likely to develop a substance use disorder, including a stronger affinity for sugar. This predisposition is also reflected in research that shows people with substance use disorder are more likely to consume more sugary foods in their diet.
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It has been hypothesized that the reason our reward system is triggered by sugar is rooted in evolutionary biology. For our ancestors gathering food to survive, bitterness in food often signaled that it was toxic, while sweet foods like fruits — or breast milk, the first food most of us ever tried — were safe.
“These pathways were built to reinforce behaviors that favored survival,” Katz said. “We still have the same cravings we had in the Stone Age, but they’re not helpful now.”
Children have a higher threshold for saccharine foods, which is why sugar-laden cereals and sweets are often targeted toward kids, Avena said. Because of the prevalence of sugar in the food supply, it’s easy for them to already develop a high tolerance for sugar before they reach adulthood, she added.
While excessive consumption of sugar has been linked to health problems like eating disorders, obesity and Alzheimer’s disease, whether sugar is harmful depends on the type and dose. Glucose, a sugar naturally circulating in the body, is so important that if we do not consume enough of it, the body will make its own. Fructose is also naturally found in honey and fruits. But added sugars like sucrolose and high fructose corn syrup are often composed of glucose and fructose chemically bound together and are primarily found in processed foods or commercially produced sugar cane.
“The only place you’re going to get pure fructose is in a fruit — and eating whole fruit is good for you, and actually reduces the risks of diabetes and obesity,” Katz said. “Otherwise, you’re getting fructose in combination with glucose for the most part.”
Altogether there are more than 60 different variants of added sugars in the food supply, and people in the U.S. consume double or triple the recommended amount of sugar in their day. Studies show this overconsumption of sugar is directly linked to an increased risk of obesity, heart disease, type 2 diabetes and non-alcoholic fatty liver disease.
“Essentially, the more of it you put into the food supply, the more of it people need to feel satisfied, and that becomes a toxic spiral, where the dose goes up and up,” Katz said. “Then the excess of sugar that isn’t needed for fueling activity is just empty calories triggering an insulin response, leading to inflammation, extra calorie consumption, weight gain, increasing the risk of insulin resistance and type 2 diabetes, and all the rest.”
However, breaking a dependency to sugar is something each person can do. Taste preferences can change, and even after a few weeks without sugar, a person’s tolerance can return to baseline. The debate over sugar being a drug or addictive rages on, but one thing they have in common is that people can consume either responsibly. Fentanyl is safely used in hospitals every day and sugar can be part of a balanced diet.
“If you do it incrementally, you actually can train your taste buds to prefer a whole different suite of foods,” Katz said. “You can love the food that loves you back.”
