What sugar does to the brain
Can our brains have a sweet tooth?
We’ve long known that sweet foods (along with fatty and salty ones) drive our cravings and lead to chronic disease in our bodies, including diminished heart health. Scientists now say they’ve vastly underestimated how our brains respond to sugar.
Growing research details how sugar affects the brain cells that influence our appetite. A study published in Cell on rodents, found that the brain not only consumes more sugar than any other organ in the body, but it actively seeks sugar from the bloodstream. We are starting to learn that excessive sugar intake can impact the brain on a molecular level, which can lead to negative outcomes such as excessive eating and eventually obesity.
“This study confirms that our eating habits are psychological at the cellular level,” says Megan Scully, a registered dietitian at Medcan, who adds that most Canadians eat more than the recommended 6 to 9 teaspoons a day (one regular can of pop contains 10 teaspoons of sugar). High-sugar diets have been linked to impaired memory and learning, depressed mood and cognitive decline.
“Since refined sugar can be hidden in even so-called “health foods”, it’s important to choose snacks and drinks that will not feed into the brain’s wiring for sugar.”
How too much sugar turns off the ‘enough’ switch
Scientists previously believed that the brain absorbed sugar as a passive action. They’ve since discovered glial cells (specifically the astrocytes that form the blood-brain barrier), which comprise about 90% of the brain’s cells, actively seek and essentially slurp sugar.
“Hormones, such as leptin and insulin, control the sugar intake into the brain through receptors on the astrocytes. This switch acts like an alarm bell to let our brains know that we are full and should stop eating. Being overweight or obese is one of the leading risk factors for developing hormone resistance and an excessive sugar intake can contribute to this,” says Scully. “We are also learning that it is possible to become leptin resistant (not just insulin resistant) – meaning, the brain doesn’t receive the signal from the adipose tissue via the leptin hormone. That means, the hunger switch remains on, even when the body has received an adequate amount of fat or sugar, which can contribute to excessive eating.”
“So this study suggests that if the brain actively seeks sugar from our bloodstream, and the ‘enough’ signal is not being activated, we may eat more than we need.”
How the body communicates with the brain
This is one more method by which the body communicates with the brain to signal fuel consumption and availability, says Dr. David Macklin, Director, Weight Management at Medcan.
“This shows us that sugar, like insulin, is a mediator effecting appetite. Current and pipeline weight loss medications target areas of the brain that mediate appetite,” says Dr. Macklin. “Theoretically, sugar affects many upstream centres of appetite regulation including critical reward physiology.”
Sugar & the reward circuit: it’s comforting and captivating
Getting the brain on board to reduce sugar intake is challenging. The brain is wired to order us to gorge on sugary and fatty foods. This wiring helped human beings in times of scarcity when such calorie-rich foods were rare.
“Sugar provides an instant ‘feel good’ or ‘comfort’ response from the release of endorphins,” says Scully. “Sugar may also reduce stress-induced circulating cortisol levels, which can work to positively reinforce the intake of comfort foods in response to stress.”
Our brains are still wired this way, but now sugary, fatty and salty foods are more easily accessible in our modern food landscape. So what to do? Banish all sugars? Scully advises moderation.
“Do not dismiss sugar entirely – specifically the natural sugars found in fruits, legumes and dairy products. Rather, recognize the added sugars hiding in so-called healthy foods like flavoured yogurt, store-bought smoothies or sports drinks, and choose better alternatives.”
Here are a few tips to reduce added sugar:
- Go gradual. Extreme changes (such as cutting out added sugar completely) are often not maintainable. To set individuals up for success, Scully encourages gradual, incremental reduction, such as cutting back the sugar you add to coffee down from 2 teaspoons to 1½ to 1 teaspoon. Most people find drastic changes difficult to maintain.
- The longer you have less sugar, you’ll start finding sweetness in surprising places. “Too much sugar desensitizes your tastebuds. Give yourself a few weeks of reduced refined sugar, and you’ll start noticing fruits or other foods taste more sweet,” says Scully.
- Buy plain yogurt and sweeten with fruit. Flavoured yogurt can have over 26 grams of sugar in the form of sauce or syrup. Best to go plain and top with real fruit and/or add cinnamon for flavour.
- Make your own smoothie. Or choose the vegetable-heavy, sugar-low options when shopping out.
- Have a designated dessert day. Enjoy your ice cream or tasty treat – one day a week. Savour the flavour and then practise restraint other days.
Sweets and savoury snacks – without refined sugar
Try a snack that combines carbohydrates, protein and natural sugars. The more you snack on these type of foods, the less you’ll crave the sugar your brain and body has become accustomed to. Here are some sample snacks to try:
- 1/4 quarter cup of unsalted almonds with 1/2 cup of blueberries
- ¾ cup of plain greek yogurt with half a cup a strawberries
- ¾ cup roasted chickpeas., flavoured with olive oil, pepper, cumin or your favourite spice.
One Sweet App monitors your sugar intake
Canadian nutrition app identifies both total and free sugar amounts for packaged foods. Scan barcodes or search the database and see the free sugar hiding in your food.
