This is your brain on an empty stomach

Cutting calories can definitely make you trimmer, and may help you live longer. Now a new Yale study suggests that dieting might also keep you mentally sharper.

Blood levels of a gut hormone called ghrelin (rhymes with “melon”) rise when the stomach is empty, flooding the brain’s eating control center and stimulating neurons that govern appetite. When Tamas L. Horvath, D.V.M., Ph.D., chair and associate professor of comparative medicine, and colleagues injected mice with ghrelin, the hormone rapidly altered circuits in the hippocampus, a brain region that is crucial to learning and memory. Ghrelin-treated mice were significantly better at learning and remembering their way around a maze.

In people, aging and obesity—two factors associated with memory loss in Alzheimer’s disease—cause ghrelin levels to fall. Horvath’s results, published in the March issue of Nature Neuroscience, suggest that shoring up ghrelin levels with weight reduction or drugs that mimic its action could help stave off dementia.