This is the first in a series of posts exploring sugar and the sweet sensation. It explains how they impact the brain, and in turn, our behavior. In a sentence, they leaving us wanting more, and send us foraging for more, because they trigger our reward center – the same one targeted by cocaine, heroin, and other addictive drugs. Part II details the mindset changes and perceptual shifts needed to change your relationship with sugar. The rest of the series will will give you actual strategies to implement and offer a 21 day challenge we can do together to experience life without them. You can scroll to the bottom for a table of contents to the series.
This series arises out of what readers have written lately on Mark’s Daily Apple about sugar, artificial sweeteners, and their effects on behavior. Specifically, people have written that sweeteners – both real and artificial – cause hunger, cravings, binging, or other regressions in their eating habits. Let’s look at some of the discussion:
- Andrew wrote that tasting anything sweet, whether it real or artificial, makes him hungry. When he was experimenting with intermittent fasting, he ran two sub-experiments. In one of them, he rinsed his mouth with sugary iced tea and spit it out without swallowing any. Within 20 minutes, intense food cravings kicked in. In another exeriment (which he ran several times), he did the same thing with artificial sweetener mixed with water. He got the same result.
- Nicole wrote, “I gave up Stevia because any added sweeteners mean big trouble for me.” Others concurred in the comments to her story: Shary (“replacing sugar with artificial sugar doesn’t eliminate the cravings”); Carrie (“Stevia might be healthier than sugar, but for some of us, replacing one type of sweetener with another doesn’t eliminate the cravings. It was much too easy to rationalize my way right back into eating sugar and junkfood until I eliminated all sweets”).
- In the comments to this post on artificial sweeteners, person after person reported hunger, cravings, overeating, or binging brought on by them. See e.g. Bryce (“I used to use sweeteners like Splenda all of the time, tons of sugar and diet soda. And I would always say ‘I don’t know why I never feel full.'”); Alyie (“If I chew gum that has artificial sweeteners, or eat sugar free candy, I just start to want real honest to god sugar.”).
What’s going on here?
When you taste something sweet, does it make you want more sweetness? Does sugar make you crave more sugar? When you stop eating sugar for an extended period, do you stop wanting sugar? What about artificial sweeteners – is their effect on you the same or different?
I need sugar like five times a day. – Kim Kardashian
Why does the mere taste of sweetness send us over the edge? We might think the answer is insulin, but we would be only partially right. It would depend on whether it’s real or artificial sugar we’re talking about. And then we’d still be missing a huge part of the answer. To find it, we’d have to look to the brain’s reward center. Which we’ll do right now, in this post. Keep reading and you’ll find out why sweets make us want more sweets, pursue more sweets, and eat more sweets.
Quick note: By “us” I mean everyone except the rare outliers who can stop eating sweets after a bite or two and not think about it or get triggered in any way by it. This post isn’t about them. It’s about everyone else (which includes me).
From your tongue to your brain
For starters, sugar is a palatable food. In everyday language, the word palatable refers to food that tastes good. Scientifically, palatable means more than that. It’s used to refer to food that has the capacity to stimulate the appetite, prompt us to eat more of it, and motivate us to pursue it.
You can never get enough of what you don’t really need. – U2
For most people, sugar has this capacity. Artificial sweeteners do as well (as we see from the reader statements above). This study shows that they can make us eat more of the sweetened food, because it’s less satisfying than real sugar (so we eat more of it to get the same effect).
What follows is a working distillation of a fairly complex process. From it, you’ll see why sweets (real and artificial) are crack-like. They’re highly salient stimuli that target the same region of the brain as crack (and alcohol and heroin and other highly salient substances). Here’s the gist of the process:
- Neurons are transmission cells in the brain. When we taste sweetness, we activate certain neurons in a primitive region of the brain called the VTA (the ventral tagmented area). The neurons produce a neurotransmitter called dopamine and send it along thread-like axons into the nucleus accumbens, the brain’s reward center. When that happens, the taste gets our attention and we start liking it.
- At that point, certain structural changes in the brain start happening that set the stage for addiction. Specifically, the VTA neurons send dopamine into the prefrontal cortex (which controls judgment and planning), which in turn instructs the hippocampus (involved in memory) to remember the sensation and the cues surrounding it. Dopamine is also sent to the dorsal stratum (where habit learning occurs), so a sugar habit begins to form, triggered by the surrounding cues. Emotion comes into play as well, because dopamine is sent to the amygdala and anterior cingular cortex (our emotion centers).
- From this process, liking becomes wanting and wanting becomes doing. That’s because wanting is the motivational state where we’re willing to work for something. This “work” is what scientists call pursuit and acquisition behavior. It’s the stuff we do to recapture and experience the liking sensation again and again.
- Key point: It’s not just the reward itself and our memory of it that leads to wanting and doing. The surrounding cues we’ve remembered do as well, because they cause a dopamine release too – right into the nucleus incumbens – like the actual reward does. So cues themselves take on salience and lead to a dopamine-fueled craving that make us work hard to obtain the reward. For example, the cues surrounding the sweet taste of chocolate – like the time of day when we have it, the people we eat it with, or a place where we buy it – lead to a dopamine release that makes us want chocolate and set about going to get some and eating it.
Thus, we go from tasting sweets to liking and wanting them to actually doing things to get them. Each taste and the cues surrounding them flood the system with dopamine, reinforcing memory, overriding choice, and continuously guiding us and our behavior in the direction of the reward.
This isn’t what the brain’s reward system is there for. It evolved to give us the motivation to learn and do behavior that brings us what we need. It’s a survival mechanism. Highly salient rewards (like sweets, drugs, and other things we can get addicted to) trick the system into believing that they’re needed for survival. They capture too much of our attention and push what’s actually necessary and useful into the background.
All the foods we like can lead to our wanting them (and to cueing and doing behavior to get them) because the brain’s reward system evolved to reinforce behaviors that benefit the species (like eating and sex). But sugar hijacks the system to an unnatural degree, the same way addictive drugs do. It exaggerates the process to the point where we keep seeking out the reward again and again. This is why tasting sweets make us want more sweets, take action to get more sweets, and eat more sweets.
Next up in this series: The mindset changes and perceptual shifts needed to change your relationship with sugar.
OVER TO YOU: What’s your experience with sugar – real and artificial. Is sweetness a big part of what you eat or drink? Is there anything you’ll only have if it’s sweetened (like coffee, for example)? Have you ever paid close attention to how you experience tasting sweets, and what flows from there?
TABLE OF CONTENTS TO THIS SERIES
Why Sugar Is So Crack-Like (& What To Do About It) …
Part I How dopamine drives us <= This post
Part II Why perceptual shifts are key
Part III Tools #1 and #2
Part IV Tools #3 and #4
NOTES & RESOURCES
John J. Ratey, M.D., Spark at 50-54, 170-72.
Gary Taub, Why We Get Fat at 142-43.
David J. Linden, The Compass of Pleasure at 15-20.
David A. Kessler, M.D., The End of Overeating at 10-12, 35-38.