What happens to your brain when you eat sugar

YOU MAY want to stop blaming your sweet tooth for all those failed dieting attempts and lolly cravings, because it turns out your brain is simply after a raw calorie hit, and not necessarily of the ‘sweet tasting’ kind.

A new study in mice has revealed the desire for calories in sugar is stronger than the drive for sweetness, meaning artificial sweeteners are ‘unsatisfying’ compared to actual sugar; because it is calories the body craves, and not the taste.

The research conducted by Yale University reveals the brain responds to taste and calorie counts in fundamentally different ways, and if given a choice, the brain will go for calories over the taste of sweetness.

“It turns out the brain actually has two segregated sets of neurons to process sweetness and energy signals,” said Ivan de Araujo of the John B. Pierce Laboratory and senior author of the study.

“If the brain is given the choice between pleasant taste and no energy, or unpleasant taste and energy, the brain picks energy.”


Sugar activates reward areas of the brain that are associated with both sweetness and the need for calories. The two separate areas of the striatum are the ventral area, which processes the sweet taste, and the dorsal area, which processes the nutritional value.

The research, which was published in Nature Neuroscience, tested the mice to see which signal had more control over eating behaviour.

It showed the mice were drawn to a solution that tasted terrible, but contained high levels of energy over the alternative; which tasted sweet, but the calorie and energy count was low.

“The sugar-responsive circuitry in the brain is therefore hardwired to prioritise calorie seeking over taste quality,” Prof de Iraujo said.

In an interview with news.com.au, nutritionist Kristen Beck spoke of how the research revealed more about why our brains become ‘hooked’ on sugar.

“The findings are fascinating because they actually identify, and even anatomically pinpoint, specific areas of our brain that play a key role in keeping us hooked both on sugar and calories,” Ms Beck said.

“While we have known for a very long time that there are many areas and pathways in our brains responsible for encouraging and rewarding us for eating sugary foods, this study identifies specific area of the brain that can work out if the sugary foods being eaten are also actually providing enough dietary energy and make these foods a priority.”


Ms Beck also spoke of how the study was a great insight in to our obsession with sugary treats.

“While our conscious, intellectual areas of our brain known as the frontal cortex, understands that eating too much sugar is bad for us, the drive for us to crave, seek out, and eat sugary and highly energy-dense foods, is coming from a more ancient, primal area of our brain,” Ms Beck said.

“Despite only being in animal studies at the moment, if comparable brain effects exist in humans, it may provide insight into why, when foods such as low-fat foods or artificial sweeteners are manufactured to ‘trick’ our bodies into consuming less energy.

“Many of us still respond to these by over consuming these foods, because our brain can still identify that it is lower in energy (calories/kilojoules) than it was expecting, so our brains haven’t been tricked at all.”

As for our addiction to the sweet stuff, Ms Beck said our obsession stems from the reward centres of our brain, and has been part of our makeup for centuries.

“Throughout human evolution, our ancestors learned that sugar and sweet foods were a highly valuable source of energy,” Ms Beck said.

“Over time, our brains have developed neural pathways that send signals to the rest of our bodies, both conscious and unconscious, to encourage us to eat sugar at every opportunity. Our brain’s reward system, or the mesolimbic pathway, then reinforces this by releasing a ‘feel good’ neurotransmitter when we eat sugary foods.

“Overloading this reward system by consistently eating sugary foods kickstarts sensations of craving and increased tolerance to sugar. Long-term, repeated intake of lots of sugary foods then leads to prolonged ‘feel good’ signalling, greater excitation of the brain’s reward pathways and a need for even more sugar. It’s basically an addiction.”

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