How junk food outsmarts our brains—by hiding in our memories

(Here’s how ultra-processed food harms the body and brain.)

Though the research was conducted in animals, it supports a growing body of evidence that memories of fat and sugar can quietly shape our eating behavior—often without our awareness. And in a world where high-calorie foods are everywhere, those neural patterns may help explain why some cravings feel impossible to resist.

Why our brains are no match for junk food

The job of any organism is to understand how to navigate and make the best choices to obtain food in their environment, says Dana Small, a psychologist, neuroscientist, and the Canada Excellence Research Chair in Metabolism and Brain.

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In early human history, when calories were scarce, we learned to use sensory cues—smell, sight, and location—to identify energy-rich foods, says Small. After eating, the brain stores that information along with how the food made us feel, creating a mental “database” of flavors and their effects. Essentially, when we eat, we’re subliminally “integrating the external and internal worlds, which is what memory is,” says Small.

These signals influence dopamine release in the brain’s reward pathways. The brain then updates the value of a food based on this information and uses that data when you reencounter the flavor. So the next time you pass a bakery, for example, that internal record, or memory, activates, sparking a craving.