Some of us can definitely say we have a sweet tooth. Whether it’s cakes, chocolates, cookies, lollies or soft drinks, our world is filled with intensely pleasurable sweet treats. Sometimes eating these foods is just too hard to resist. But is it actually "additive" in a biological sense? Let's take a look at the science.
As a nation, Australians consume, on average, 60 grams (14 teaspoons) of table sugar (sucrose) a day. Excessive consumption of sugar is a major contributor to the increasing rates of obesity in both Australia and globally.
Eating sugary foods can become ingrained into our lifestyles and routines. That spoonful of sugar makes your coffee taste better and dessert can feel like the best part of dinner. If you’ve ever tried to cut back on sugar, you may have realised how incredibly difficult it is. For some people it may seem downright impossible. This leads to the question: can you be addicted to sugar?
Sugar activates the brain’s reward system
Sweet foods are highly desirable due the powerful impact sugar has on the reward system in the brain called the mesolimbic dopamine system. The neurotransmitter dopamine is released by neurons in this system in response to a rewarding event.
Drugs such as cocaine, amphetamines and nicotine hijack this brain system. Activation of this system leads to intense feelings of reward that can result in cravings and addiction. So drugs and sugar both activate the same reward system in the brain, causing the release of dopamine.
This chemical circuit is activated by natural rewards and behaviours that are essential to continuing the species, such as eating tasty, high energy foods, having sex and interacting socially. Activating this system makes you want to carry out the behaviour again, as it feels good.
The criteria for substance use disorders by the Diagnostic and Statistical Manual of Mental Disorders (DSM 5) cites a variety of problems that arise when addicted to a substance. This includes craving, continuing use despite negative consequences, trying to quit but not managing to, tolerance and withdrawal. Although sugary foods are easily available, excessive consumption can lead to a number of problems similar to that of addiction. So it appears sugar may have addictive qualities. There is no concrete evidence that links sugar with an addiction/withdrawal system in humans currently, but studies using rats suggest the possibility.
Dopamine has an important role in the brain, directing our attention towards things in the environment like tasty foods that are linked to feelings of reward. The dopamine system becomes activated at the anticipation of feelings of pleasure.
This means our attention can be drawn to cakes and chocolates when we’re not necessarily hungry, evoking cravings. Our routines can even cause sugar cravings. We can subconsciously want a bar of chocolate or a fizzy drink in the afternoon if this is a normal part of our daily habits.
Repeated activation of the dopamine reward system, for example by eating lots of sugary foods, causes the brain to adapt to the frequent reward system stimulation. When we enjoy lots of these foods on a regular basis, the system starts to change to prevent it becoming overstimulated. In particular, dopamine receptors start to down-regulate.
Now there are fewer receptors for the dopamine to bind to, so the next time we eat these foods, their effect is blunted. More sugar is needed the next time we eat in order to get the same feeling of reward. This is similar to tolerance in drug addicts, and leads to escalating consumption. The negative consequences of unrestrained consumption of sugary foods include weight gain, dental cavities and developing metabolic disorders including type-2 diabetes.
Quitting sugar leads to withdrawal
Sugar can exert a powerful influence over behaviour, making cutting it out of our diets very difficult. And quitting eating a high sugar diet “cold turkey” leads to withdrawal effects.
The length of unpleasant withdrawal symptoms following a sugar “detox” varies. Some people quickly adjust to functioning without sugar, while others may experience severe cravings and find it very difficult to resist sugary foods.
The withdrawal symptoms are thought to be factors of individual sensitivity to sugar as well as the dopamine system readjusting to a sugar-free existence. The temporary drop in dopamine levels are thought to cause many of the psychological symptoms including cravings, particularly as our environment is filled with sweet temptations that you now have to resist.
Why quit sugar?
Cutting sugar from your diet may not be easy, as so many processed or convenience foods have added sugars hidden in their ingredients. Switching from sugar to a sweetener (Stevia, aspartame, sucralose) can cut down on calories, but it is still feeding the sweet addiction. Similarly, sugar “replacements” like agave, rice syrup, honey and fructose are just sugar in disguise, and activate the brain’s reward system just as readily as sucrose.
Physically, quitting sugar in your diet can help with weight loss, may reduce acne, improve sleep and moods, and could stop those 3pm slumps at work and school. And if you do reduce sugar consumption, sugary foods that were previously eaten to excess can taste overpoweringly sweet due to a recalibration of your sweetness sensation, enough to discourage over-consumption!
This article was originally published on The Conversation.