09/30/2025
It only takes four days of junk food to mess with your memory.
Researchers found that high-fat diets – think cheeseburgers, fries, and pizza – can disrupt key memory circuits in the brain almost immediately.
This has nothing to do with weight gain or diabetes. The effect hits long before any of that.
Scientists looked at mice fed a fatty diet, and within just four days, something alarming happened: special neurons in the hippocampus – the brain’s memory hub – became overactive. These cells, known as CCK interneurons, help regulate memory formation. But when deprived of glucose, their activity surged, scrambling how the brain stores and retrieves memories.
Normally, CCK interneurons act like brakes in the system – moderating the firing of other neurons so that memory processes stay stable. But the high-fat diet altered how these cells used energy. It limited the brain’s access to glucose – its preferred fuel – and triggered a metabolic shift. In response, the CCK interneurons started firing more than they should. That overactivity scrambled the hippocampus’ ability to encode and retrieve memories.
The researchers also identified a protein called PKM2, which helps control how brain cells metabolize energy. In the junk food-fed mice, PKM2 seemed to push neurons toward a less efficient energy state, worsening the problem.
But there was good news: when researchers restored glucose – or introduced short periods of fasting – the CCK interneurons returned to normal, and memory function improved. Just giving the brain access to the right fuel source was enough to calm things down.
This suggests that memory loss linked to obesity may not just be a slow, years-long process. It could begin almost immediately – and be reversible with early intervention.
Read the study:
"Targeting glucose-inhibited hippocampal CCK interneurons prevents cognitive impairment in diet-induced obesity." Neuron, 2025.
