A new study from researchers at the UNC School of Medicine has found that eating junk food doesn’t just affect your waistline—it can scramble your memory in as little as four days. Scientists discovered that a diet high in saturated fats, like cheeseburgers and fries, overstimulates certain brain cells in the hippocampus, the brain’s memory hub. These cells, called CCK interneurons, become overactive when the brain can’t get enough glucose, or sugar, from food. Dr. Juan Song, the lead researcher, said what surprised the team most was “how quickly these cells changed their activity” and how even short-term junk food exposure caused problems. Choosing healthier meals—even just most of the time—may be one of the best ways to keep your memory strong for years to come.