Less intense than cocaine and heroin, but nonetheless addictive for some people, sugar activates the same region in the brain that makes you experience a high and feelings of pleasure. Like using hard drugs, bingeing on sugar blunts the “pleasure” response over time, making you want the sugar fix more frequently and in higher doses to experience the same feelings of pleasure. This has dire consequences on some processes in the body.
The biochemical effects of sugar:
In the 1960’s and 1970’s the buzz words in food and diet became “low fat”, following on (largely incorrect) assumptions that obesity and related metabolic syndrome disease (characterized by abdominal obesity, high triglycerides, high blood pressure, high blood glucose, and low HDL cholesterol) were caused by food high in fat, including the healthy fats. Food manufactures reduced the fat content, but to make the processed food still palatable, they added sugar to improve the taste. Scientists claim this was the start of the worldwide obesity pandemic.
The first mouthful of sugar activates the taste receptors on the tongue and sends a signal to the cerebral cortex in the brain, which then signals the brain’s pleasure and reward center (limbic region), basically asking do you like it or not? The reward center confirms and asks for more of the same. The brain then spikes the release of a neurotransmitter called dopamine that makes you experience feelings of pleasure, also released during and after sex (the brain perceives sex as important for procreation), when taking recreational drugs such as heroin and cocaine, also during intake of alcohol and nicotine, and during pleasant social contact. Sugar does not produce the extreme dopamine spikes that hard drugs do, but over the long term the daily sugar overdoses can lead to cravings and increased tolerance to sugar – meaning you need more to get the same feelings of pleasure.
Hard drugs cause the brain to flood with dopamine, which tricks the brain to believe that the drugs are necessary and important. Over time the brain adjusts to release less dopamine, requiring use of the substances in increasing amounts and frequencies, which leads to substance abuse and addiction.
From the mouth the sugar travels to the stomach and gut, where sugar receptors send signals to the brain when you reach satiety, as well as signals to activate the production of insulin to regulate blood sugar levels. Once again, daily overindulgence in sugar increase the tolerance to sugar, making you eat sugar more frequently and in larger quantities for the same effect. Other carbohydrates such as starch, lactose (sugar in milk), and dextrose (sugar made from starches from corn, wheat, and rice) are also classes of sugar.
An interesting sugar tidbit – research on laboratory rats found that Oreo cookies activate more neurons in their brains’ pleasure center than cocaine does. Like most of us, the rats would eat the filling first!
Chemical reactions in the body
Sugar (sucrose) consists of glucose and fructose molecules in equal amounts.
Glucose is the primary source of energy for every cell in the human body. The brain, being rich in neurons or nerve cells, is a very energy demanding organ and uses half of all the glucose energy in the body. About 20% of glucose ends up in the liver, where it is stored as the liver starch, glycogen, which is released as fuel for energy whenever blood glucose levels run low. The rest of the glucose goes to all the organs and cells in the body.
Fructose, on the other hand, only gets metabolized in the liver. Unfortunately, only a limited amount of fructose is metabolized in the liver, the rest is turned into lipid (fat) molecules, called triglycerides. Excess triglycerides can build up in liver cells, where these “fat spots” can cause liver damage, leading to fatty liver disease, while the rest are released into the bloodstream, and the bulk gets stored in fat cells.
Triglycerides and cholesterol are different types of fat circulating in the bloodstream. While triglycerides store unused calories and can provide the body with energy, cholesterol is used to build cell membranes and certain hormones. High levels of triglycerides (and cholesterol) in the blood may be a sign of diabetes or metabolic syndrome. It can contribute to hardening of arteries, thickening of artery walls, and build-up of fat-filled plaque inside artery walls – increasing the risk of stroke, heart attack, and heart disease.
The high levels of fructose in the modern diet is one of the main culprits causing the worldwide obesity and metabolic disorder pandemic, says scientists such as Dr Robert H Lustig, a professor of pediatrics and an obesity specialist at the University of California, San Francisco. Metabolic disorders are not limited to obese people, as up to 40% of people with normal weight are also affected by metabolic syndrome. Along the same lines, up to 20% of obese people are metabolically normal and without the diseases linked to metabolic syndrome.
Consuming too much sugar over time can also affect the natural balance of insulin and leptin hormones. Increased levels of glucose in the bloodstream triggers the pancreas to release more insulin, which tells the cells to pick up sugar from the bloodstream. Over time repeated spikes in blood sugar levels can prevent cells responding correctly to insulin, and cells can become increasingly resistant to insulin signalling, resulting in high levels of both blood insulin and glucose levels. The overworked pancreas can become damaged over time and decreases the production of insulin, failing to regulate blood glucose levels adequately. When blood glucose levels exceed a certain threshold, it will most probably result in diabetes.
High fructose intake from refined sugar is associated with insulin resistance and overindulgence of sugar has also been associated with aging (of the cells in our bodies), Alzheimer’s disease, and indirectly contributing to an increased risk of some cancers, linked to obesity.
The hormone leptin tells our brains when we have reached satiety and the brain then sends signals to stop eating. High consumption of fructose over time has been associated with leptin resistance, which means the brain does not get the satiety message to stop eating, but instead the brain assumes you are still hungry and need more food!
To make matters worse, insulin also plays a role in satiety signals to the brain. During normal metabolism after a meal, insulin tells the fat cells to store energy and signals the brain to stop eating and stop feeding the fat cells. However, insulin resistance often goes hand in hand with leptin resistance.
How to kick the sugar habit:
If you have a sweet tooth or a real love for sugar, but are concerned of its dire effects on the body, the best way to kick the habit is to gradually cut down on sugar intake. Suddenly quitting a high sugar diet can result in unpleasant withdrawal effects, due to individual sensitivity to sugar and the dopamine system readjusting to the absence of sugar. Our taste buds do adapt to less sugar and over time the cravings will subside. Thereafter the sugary foods that you previously ate excessively, will taste overpoweringly sweet.
Once weaned of high sugary foods, try to indulge in sugary treats only on extremely rare occasions, lest your brain starts to demand sugar loudly and often again!
Sources:
Fat chance: Fructose 2.0. Transcription of talk 24 May 2014 on his book Fat Chance, by Dr. Robert Lustig, Professor of Pediatrics, Endocrinology Division, University of California, San Francisco. (www.robertlustig.com)
The toxic truth. Too much fructose can damage your liver, just like too much alcohol. Published online. Sugar Science. University of California, San Francisco. (www.sugarscience.ucsf.edu)
Sugar and dopamine: the link between sweets and addiction. Published online. Wellness Retreat Recovery Center. (www.wellnessretreatrecovery.com)
Why our brains love sugar – and why our bodies don’t. Published 5 February 2013. Psychology Today. (www.psychologytoday.com)
Experts agree – sugar may be as addictive as cocaine. Published 30 April 2020. Healthline. (www.healthline.com)
Fact or fiction: is sugar addictive? Published 22 February 2017. The Conversation. (www.theconversation.com)
How does sugar affect the brain? Published online. Science Alert. (www.sciencealert.com)
Insulin and insulin resistance – the ultimate guide. Published 24 July 2019. Healthline. (www.healthline.com)
HEALTH INSIGHT
