Houston, we have a problem
Not only do sweet foods increase dopamine levels, but over-consumption of sweet foods can actually cause a breakdown in brain chemistry. According to a study published in Nature Neuroscience, “common mechanisms may underlie obesity and drug addiction.” (3) Researchers found that when animals were given a diet of high calorie foods, there was a significant reduction in the activity of their dopamine receptors. This is very similar to the affect that cocaine or heroin has on the brain. (3)
What does decreased receptor activity mean? It means that the brain becomes tolerant to dopamine signals. This is similar to what happens when you go to a concert. When you first get there, the music seems very loud. But as the concert goes on, you get used to the noise level, and it no longer seems as loud as it did when the band started playing – you become tolerant to the noise level. That’s exactly what happens with dopamine in the brain. If you are constantly eating or seeing sweet, high-calorie foods, your dopamine levels are always high, just like the music at the concert is always loud. Your brain gets used to the high dopamine levels and starts tuning them out. The signal does not seem as strong anymore. This means that you will need more dopamine to feel any effect, just like the music would have to be turned up for you to notice any change in volume.
For someone with constantly high dopamine levels, more and more sweet, high-calorie foods are needed to get the same kind of pleasure. This sets many people up for a catch-22 situation – they remember how great something a certain food made them feel and expect it to bring them the same amount of pleasure. However, when they eat the food they aren’t as satisfied as they expected to be, so they eat more and more in hopes of regaining that original feeling (or ‘high’). This often becomes a cycle of constantly elevated dopamine levels, leading to decreased dopamine receptor response, causing decreased pleasure and constant attempts to achieve more pleasure (by raising dopamine levels even higher) by eating more and more super-sweet, high calorie foods. (4) This should start to sound a lot like addiction.
Studies have shown that people with addictive-like eating behaviors – which includes addiction to sweet, high-calorie foods, insatiable cravings and binge eating – have greater brain activity in regions associated with substance dependence and abuse. They also have increased activity in their reward circuitry and less activity going on with inhibitory regions of the brain (5). This means that they are more prone to seek out pleasure-inducing experiences and less likely to be able to stop themselves in the process. Their reward systems are being triggered at a higher rate than people who don’t have addictive-like eating behaviors, and they are less able to keep themselves from acting on their desires.
Some professionals have questioned whether sugar addiction, and addictive behavior in general, is due more to willpower or genetics. We know that there are a decreased number of dopamine receptors in the brain in both drug addicts and in obese people. The question is whether the decreased number is due to the brain trying to compensate for the abnormally high levels of dopamine or just because those people were born with lower levels of receptors. (2) The evidence to date seems to indicate that it could be a bit of both, with the compensation piece playing a much larger role. For instance, research has shown that the more obese a person is, the fewer dopamine receptors they have (2). This seems to suggest that the brain has built up a tolerance to the high levels of dopamine. Regardless of cause, a person with a decreased number (or function) of dopamine receptors would require more stimulation than the average person to feel the same amount of pleasure, putting them at greater risk for addictive behaviors. (6)
The final criterion for addiction is evidence of withdrawal. Withdrawal symptoms from sugar addiction can occur within a few hours to several days after discontinuation depending on the person and severity of sugar use. Carvings, often moderate to severe, are the most common withdrawal symptom; people often also have an increased appetite, especially for sweet foods. However, some people have much more severe symptoms, including depression, anxiety, mood swings and an extreme drive to continue eating sugar despite the significant harm it is causing them. People that experience these types of symptoms usually have very low levels (or very low functioning) of dopamine receptors due to years and years of sugar use. Once the sugar is discontinued, there is not enough dopamine to help them feel ‘normal’ and they can feel like their world is crumbling around them. This is why many people need guidance and support to help them break their sugar addiction.
The final part of this three part series will detail how you can break your sugar addiction and free yourself from the daily cravings and binges that can thwart even the best-laid intentions.
- “Can sugar be addictive?” foodnavigator.com. William Reed Business Media, 16 Jan. 2006.
- Leutwyler Ozelli, Kristin. “This is your brain on food.” Scientific American Sep. 2007: 84-85.
- Daniells, Stephen. “Food addiction: Fat may rewire brain like hard drugs.” foodnavigator.com. William Reed Business Media, 29 Mar. 2010.
- Gardner, Amanda. “Compulsive Eaters May Have ‘Food Addiction,’ Study Finds.” healthday.com. Health Day, 4 Apr. 2011.
- Gray, Nathan. “Food addiction has similar brain response to drug addiction: Study.” foodnavigator.com. William Reed Business Media, 5 Apr. 2011.
- Hyman, Mark MD. “Stopping Addiction to Sugar: Willpower or Genetics?”
- Scott-Thomas, Caroline. “Animal study suggests existence of sugar addiction, says scientist.” foodnavigator.com. William Reed Business Media, 11 Dec. 2008.
- Scott-Thomas, Caroline. “Sugar addiction ‘unlikely in humans,’ says scientist.” foodnavigator.com. William Reed Business Media, 9 Jan. 2009.