MONTPELLIER, France — Snacking on junk food in between meals could mean a rough end to the workday. Researchers in France have found that eating too many processed carbs (like sugar and white bread) can affect the way our brains work.

A team from the University of Montpellier explain that when we eat a lot of these types of foods, our bodies produce a hormone called insulin to help deal with all the sugar in our bloodstream. When we keep eating these foods, however, we can become insulin-resistant, which means our bodies don’t respond to insulin like they should.

The new study suggests that this could lead to a decline in cognitive abilities — which includes our thinking, memory, and learning skills. The researchers wanted to see if this happens in young, healthy adults, so they gathered 95 people between the ages of 20 and 30 in France to be part of the study. The participants had to be healthy, regularly eat breakfast, and not have any food allergies.

From there, the team tested the cognitive abilities of these young adults and also kept track of what they ate, especially during breakfast, afternoon snacks, and other snacks between meals. These are the times when people often eat foods high in processed carbs.

Woman eating snacks and junk food while working at desk
(© Juliaap –

The findings reveal that if the participants had a habit of eating a lot of processed carbs, especially during snack times, their performance in cognitive tests dropped off. This means they might have had some trouble with learning or problem-solving skills.

One important point the researchers make is that this relationship remained even after considering other factors, like how many total calories the participants ate each day. So, it seems that it’s not just about eating a lot of food, but specifically about eating a lot of processed carbs that could potentially affect brain function.

In short, this study suggests that continually eating a lot of processed carbs, like sugary snacks, could make it harder for us to think and learn, even when we’re still young and healthy.

The study is published in the journal Personality and Individual Differences.

Junk food can literally ‘brainwash’ you

In a separate study, eating food high in sugar and fat rewires our brains to unconsciously prefer delicious but unhealthy treats.

The study team, led by Dr. Marc Tittgemeyer, observed that the brain’s responses to sugar and fat-rich foods in a group that ate daily high-fat and sugar desserts were greatly increased after an eight-week experiment. This increased activity especially activated the “dopaminergic” system, which releases the feel-good hormone dopamine in the region of the brain responsible for motivation and reward.

“Our measurements of brain activity showed that the brain rewires itself through the consumption of chips and [other junk food]. It subconsciously learns to prefer rewarding food. Through these changes in the brain, we will unconsciously always prefer the foods that contain a lot of fat and sugar,” Dr. Tittgemeyer says in a statement.

Our craving for junk food may actually be an evolutionary trait

In 2020, scientists in the Netherlands found that our craving to find hidden snacks in our kitchens isn’t just about good memory, the human brain may actually be wired to hunt down high-calorie food.

A team from Wageningen University & Research believes the human brain has evolved to focus on memorizing where high-calorie foods are located. Study authors theorize this allowed our hunter-gatherer ancestors to survive in tough environments with few food options.

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