Brain Plugs

Your Body Recognizes Sugar as a 'Drug'

Previous research involving humans and laboratory rats suggests consumption of sugar and sweets can trigger reward and craving states in your brain similar to addictive drugs. Not only can sugar and sweets substitute for drugs like cocaine, in terms of how your brain reacts to them, they can be even more rewarding.

The dramatic effects of sugar on your brain may explain why you may have difficultly controlling your consumption of sugary foods when continuously exposed to them. Another study suggests a high degree of overlap exists between brain regions involved in processing natural rewards, such as sugar and sweets, and drugs of abuse.

"'Non-drug' or 'behavioral' addictions have become increasingly documented and pathologies include compulsive activities such as shopping, eating, exercising, sexual behavior and gambling. Like drug addiction, non-drug addictions manifest in symptoms including craving, impaired control over the behavior, tolerance, withdrawal and high rates of relapse."

How Bad Habits Like Sugar Addiction Take Root

An article published by CNN Health5 reminds us that the connection between your nucleus accumbens and prefrontal cortex drives intentional actions, such as deciding whether you will take another bite of chocolate cake, for example.

Your prefrontal cortex also activates hormones like dopamine, triggering thoughts such as, "Hey, this cake is really good. And I'm going to remember that for the future." Lustig explains the biological process that takes place when you consume sugar or any addictive substance:6

"Every time you follow the same path, a specific pattern is activated and becomes more defined … and it becomes easier to activate the circuit the next time. Pretty soon, the bad habit neuronal pathway becomes the unconscious default, and your brain, wanting to be efficient, just takes the easiest, most familiar route. This is particularly true in the case of depression.

In a depressed brain, there's less dopamine activity happening in the nucleus accumbens, which means that things that used to be enjoyable are not as pleasurable, and the only things that motivate it have to have a big dopamine payoff, which are the baddest of the bad habits, such as junk food, drugs, alcohol [and] gambling."

Brain Imaging Shows Food Addiction Is Real

Research published in the American Journal of Clinical Nutrition8 examined the effects of high-glycemic index (GI) foods on brain activity, using functional magnetic resonance imaging (fMRI). Twelve overweight or obese men between the ages of 18 and 35 consumed one high-GI and one low-GI meal.

Imaging was completed four hours after each test meal to assess the cerebral blood flow as a measure of resting brain activity. The researchers expected brain activity to be greater after the high-GI meal in regions related to craving, eating behavior and reward.

The study demonstrates what you may experience when eating a high-GI meal. After rapidly digesting net carbohydrates, your blood sugar initially spikes, followed by a sharp crash later. As noted by researchers, this crash in blood glucose stimulated greater brain activity in the nucleus accumbens, the brain's pleasure center Lustig mentioned above.

Can Too Much Sugar Contribute to Alzheimer's Disease?

While insulin is usually associated with its role in keeping your blood sugar levels in a healthy range, it also plays a role in brain signaling. In one animal study, when researchers disrupted the proper signaling of insulin in the brain, they were able to induce many of the characteristic brain changes seen with Alzheimer's disease, including confusion, disorientation and the inability to learn and remember.

It's becoming increasingly clear that the same pathological process that leads to insulin and leptin resistance, as well as type 2 diabetes, may also hold true for your brain. As you overindulge on sugar and grains, your brain becomes overwhelmed by the consistently high levels of insulin. Eventually insulin, leptin and signaling become profoundly disrupted, leading to impairments in your memory and thinking abilities.

A study published in Diabetes Care found that type 2 diabetes is associated with a 60 percent increased risk of dementia in men and women. Research featured in the New England Journal of Medicine noted a mild elevation of blood sugar, such as a level of 105 or 110, is also associated with an elevated risk for dementia.

Dr. David Perlmutter, neurologist and author of the books "Brain Maker" and "Grain Brain," believes Alzheimer's disease is primarily predicated on lifestyle choices, including sugar consumption. He suggests anything that promotes insulin resistance will ultimately also raise your risk of Alzheimer's.

How Do They Affect Your Brain?

Increases in processed fructose consumption, typically in the form of high-fructose corn syrup (HFCS), seem to be running parallel to the spikes seen in obesity rates, so much so that diets high in it are thought to promote insulin resistance and weight gain. The Journal of the American Medical Association featured a study12 involving 20 adult volunteers who underwent magnetic resonance imaging sessions at Yale University to identify neurophysiological factors related to fructose versus glucose consumption.

The research suggests fructose a type of sugar commonly extracted from corn and found in sweetened products like soda — may activate brain pathways that increase your interest in food, whereas glucose ingestion appears to trigger your brain's satiation signal, effectively telling you "you've had enough." When participants ingested glucose and were then shown food pictures, their brains registered increased measures of satiety and fullness.

Subsequent research,14 presented in the Proceedings of the National Academy of Sciences USA, went a step further to investigate the effects of sugar on food-approach behavior. After ingesting either fructose or glucose, 24 volunteers underwent two fMRI sessions while viewing pictures of high calorie foods and nonfood items in a block format.

Both of these studies underscore the importance of paying attention to the type of sugars you consume. Clearly, fructose disrupts your brain's signaling mechanism that is designed to tell you when you've had enough. Because fructose fails to stimulate insulin, which in turn fails to suppress ghrelin, or "your hunger hormone," which then fails to stimulate leptin or "your satiety hormone," you are likely to eat more and develop insulin resistance when consuming fructose.

How to Manage and/or Limit Your Sugar Consumption

Sugar, in its natural form, is not inherently bad when consumed in amounts that allow you to burn fat as your primary fuel. However, you should avoid all sources of processed fructose, particularly processed foods and beverages like soda. According to SugarScience.org, 74 percent of processed foods purchased from the grocery store contain added sugar.15

Other sources have suggested it may be as high as 80 percent. I recommend your diet be composed chiefly of naturally occurring whole foods, with 10 percent or less coming from processed foods.

I also recommend severely limiting your consumption of refined carbohydrates found in cereal, bread, pasta and other grain-based foods, as they break down to sugar in your body, which increases your insulin levels and causes insulin resistance. As a general recommendation, I suggest you keep your total fructose consumption below 25 grams per day, including whole fruit. Keep in mind while fruits are rich in nutrients and antioxidants, they naturally contain fructose.