Have you ever tried to go a week without eating any sugar? What about just one day? Believe it or not, this is an impossible task for an alarming number of Americans. Sugar is hidden in nearly everything that we eat – a smoothie from the organic shop that you deem to be healthy actually has 40 grams of sugar, a piece of gluten free chocolate cake contains twice the recommended daily serving, and even the green juice from Whole Foods has more sugar than a can of Coca-Cola! The scary reality is that even if your ingredient label does not list sugar, it more than likely contains it disguised by some other name (dextrose, fructose, galactose, lactose, caltose, sucrose, etc). Last week, we discussed the negative effect that sugar has on our body and how it is the cause of nearly all chronic diseases. This week we turn to how sugar hijacks our brain chemistry and keeps us coming back for more.
The average American consumes 152 pounds of refined sugar each year. Why? Obviously, things that contain sugar taste good. But what most people do not understand is that sugar causes a neurological response within our brains. In 2008, a study out of the University of Bordeaux in France shocked the nutrition world. In the study, lab rats were given the choice of consuming cocaine or sugar. Overwhelmingly, the rats favored the sugar over the cocaine. Another study tested rats who were already addicted to cocaine. In this particular study, when the rats were presented with sugar, they forgot about cocaine entirely and repeatedly indulged in the sugar. These studies finally provided some context as to why Americans were becoming so fat so rapidly – sugar is addicting!
When you take a bite of a chocolate bar, the sugar activates the sweet taste receptors (part of the taste buds) on your tongue. These receptors send a signal to the reward system located in our brains. This reward system is a series of electrical and chemical pathways across several different regions of the brain. The major currency of the reward system is dopamine; as these signals are fired, your brain becomes filled with dopamine. Your brain then asks its reward system, “should I eat another bite of chocolate?” And your reward system screams “YES”. So, you take another bite of the chocolate bar. And then another. And just a few moments later, the chocolate bar is gone and you’ve consumed a quick 17 grams of sugar. This stimulation of the reward system is the same process that occurs with drugs, alcohol, sex, and gambling. Similar to these vices, over stimulation of the reward system with sugar kick starts the series of unfortunate addiction events – dependence, tolerance, cravings, and withdrawal.
Sugar’s addictive capabilities are two-fold; sugar causes a stimulation of the reward system in the brain and also a deceptive feeling once it reaches the stomach. Have you ever felt “hangry” before? You haven’t eaten in a while and you start to feel extremely hungry, a bit light-headed, and oftentimes irritable. This is because you have an elevated level of ghrelin in your body. Ghrelin is a hormone that is produced within the stomach, and its job is to send a signal to the brain to tell it that your stomach is empty and needs to eat. Once we eat, our ghrelin levels lower because our stomachs are full and we are no longer hungry. Foods that are high in protein and fiber lower your ghrelin levels quickly once you consume them – this is why you feel fuller faster when you eat foods dense in these nutrients. Sugar on the other hand, deceives the ghrelin hormone, and makes you feel less satiated. And that’s why after you finish that first chocolate bar, you’re still hungry!