Why is Sugar So Addictive? (SQ-6)
If you have you ever tried to cut back on sugar, you may know how incredibly tough it is to wean yourself off from the sweet devil. In fact, eliminating sugar from the diet may leave some people with strong withdrawal symptoms such as intense cravings, headaches, edginess, feeling of depression and worse. Sounds like substance addiction? Well, science suggests that sugar is even more addictive than cocaine . You heard it right. That gorgeous piece of chocolate cake or those delectable muffins seem to serve the same purpose as crack. So, what makes sugar so addictive? Why it does often makes you lose control? What exactly drives sugar cravings?
Sugar addiction: How our brain responds to sugar
Scientists believe that the mystery lies in how our brain responds to sugar intake. It appears that sugar has a profound effect on the brain’s reward centre, which makes it function like it would with drug stimulants such as cocaine. In fact a 2013 study suggests that “sugar and sweetness can induce reward and craving that are comparable in magnitude to those induced by addictive drugs….can not only substitute (for) addictive drugs, like cocaine, but can even be more rewarding and attractive.” 
Sugary delights stimulate the pleasure centres in the brain – an action that triggers changes in both brain and behaviour. Let’s see how sugar captures the brain chemistry and fools us into craving more. But first, let’s get a grip on how the brain reward centre works.
The reward pathway comprises of several structures in the brain, including the ventral tegmental area (VTA), the nucleus accumbens, hippocampus and amygdala. When this pathway is activated by a rewarding stimulus – whether it is a particularly satisfying meal, meeting with friends, having sex, getting a promotion or using a psychoactive drug – massive amounts of dopamine is released by VTA, especially in the nucleus accumbens region, a cluster of nerve cells underneath the cerebral cortex. In fact, the release of this neurotransmitter in nucleus accumbens is so much associated with pleasure that “neuroscientists refer to the region as the brain’s pleasure center.” The hippocampus, responsible for laying down memories, registers this as a happy memory, while amygdala establishes a connection between the environmental clues and the memory to create a conditioned response to particular stimuli.
Dopamine not only contributes to the feeling of happiness and pleasure, it also plays a role in learning, memory and motivation – stimulating one to see the reward and also to motivate to work hard for the reward. In a nutshell, when our brain feels rewarded, it remembers this pleasurable memory and wants it repeated. “According to the current theory about addiction, dopamine interacts with another neurotransmitter, glutamate, to take over the brain’s system of reward-related learning. This system has an important role in sustaining life because it links activities needed for human survival (such as eating and sex) with pleasure and reward.” 
What’s interesting is that from an evolutionary perspective, our brains are hard-wired to find certain things enjoyable and satisfying, such as eating or sex. These activities trigger the reward circuit in the brain to make sure we are motivated to carry out and repeat certain behaviours that are important for survival. Sugar also stimulates this reward circuitry in a similar manner. And what pushes the envelope is that our yearning to bite into sugary delights is an evolutionary hangover passed onto us from our ancestors in their bid to survive and pass along their genes.
Have a sweet tooth? Blame it on our ancestors
According to Daniel Lieberman, an evolutionary biologist at Harvard University, "Sugar is a deep, deep ancient craving." Millions and millions of years ago, our hunter-gatherer ancestors relied on sugar rich fruits as a source of energy, fat and also Vitamin C and other important micro-nutrients that would be otherwise difficult to get from animal products. Their bodies also learned to store sugar and convert sugar into fat. All these survival tactics came in handy in the harsh backdrop of food scarcity and inconstant meals, and helped them to reproduce.
It turns out that our ancestors developed a sense of taste that coveted sugar, fat and even salt as an important adaptive strategy – to supply energy for survival and then to stimulate the brain reward circuit by releasing dopamine, a feel-good brain chemical. This feedback loop helped our hunter-gatherer ancestors to crave sugar and survive better. And in the process we trained ourselves to identify sugar as an important energy source and hanker for it.
Many scientists suggest that we are born with a sweet tooth and our affinity for sugary foods begins at birth. A study from Washington University found that infants and children have a heightened preference for sweet tasting foods and drinks than adults and this preference is not “solely a product of modern-day technology and advertising but reflects their basic biology.” 
Sugar and brain chemistry
So, we are genetically programmed to have a special affinity for all things sugary. And on top of that, regular gorging on sugary foods seems to flood the nucleus accumbens shell with dopamine  – the neurotransmitter that controls the brain’s reward and pleasure centre – giving us an instant lift. This bio-chemical change explains our tendency to turn to sugary treats when we want to celebrate or when we are feeling sort of blue and crave some ‘comforting food’. But what happens when we start binging on such treats frequently?
The dopamine receptors in the brain start to down regulate, which means your brain sort of develops tolerance to the effect. There will be a reduction in dopamine receptors – desensitizing the brain to the sugar and diluting the pleasure effect. Now, the pleasure may have dulled but the memory and the desire to recreate that pleasurable effect is still there. The result is you crave for more sugar in order to experience the same level of reward or pleasure. You are invariably caught in the addictive snare – leading to insatiable sugar craving and loss of control over sugar intake. In other words, you are always seeking a high, a common occurrence with any substance intake.
We may have retained this deep rooted desire for sugar from the stone-age when the food was limited but with the easy accessibility of sugar today, excessive consumption is fast becoming a serious health concern. Lieberman explains further : “Simply put, humans evolved to crave sugar, store it and then use it. For millions of years, our cravings and digestive systems were exquisitely balanced because sugar was rare. Apart from honey, most of the foods our hunter-gatherer ancestors ate were no sweeter than a carrot. The invention of farming made starchy foods more abundant, but it wasn’t until very recently that technology made pure sugar bountiful.”
There is a lot more sugar available to us today, hidden in the processed food items we eat almost daily. These hidden sugars are sneaky and even before you realize, the sweet lure hijacks your brain’s chemistry and guess what - you are hooked! Scientific evidence shows that that sugar addiction is for real and in fact very dangerous. Excessive sugar consumption is one of the leading factors behind the obesity epidemic and is also linked to chronic inflammation, diabetes, insulin resistance, high blood pressure, premature skin aging and even depression.
Are you ready to take steps to break away from this vicious cycle of sugar addiction? Start with cutting back on added sugars and artificial sweeteners from your diet and adopt a physically active lifestyle. We, clearly, didn’t evolve to eat energy dense food and simply sit most of the waking hours.
- Lenoir M, Serre F, Cantin L, Ahmed SH. Intense sweetness surpasses cocaine reward. PLoS One. 2007
- Ahmed SH, Guillem K, Vandaele Y. Sugar addiction: pushing the drug-sugar analogy to the limit. Current opinion in clinical nutrition and metabolic Care. 2013 Jul;16(4):434-9. doi: 10.1097/MCO.0b013e328361c8b8.
- Understanding Addiction. How Addiction Hijacks the Brain. Helpguide.org. Harvard
- Ventura, Alison K; Mennella, Julie A. Innate and learned preferences for sweet taste during childhood. Current Opinion in Clinical Nutrition & Metabolic Care. July 2011 - Volume 14 - Issue 4 - p 379–384
- Rada P, Avena NM, Hoebel BG. Daily bingeing on sugar repeatedly releases dopamine in the accumbens shell. Neuroscience. 2005;134(3):737-44.
- Daniel E. Lieberman. Evolution’s Sweet Tooth. The New York Times. 2012.