The human body was designed to love fatty foods in part because of the needs of the brain. We should choose the “good” kinds of fats, skipping the dangerous ones and adding plenty of brain-healthy ones. The brain is made mostly of fat. Fat forms the membranes around cells and also insulates the bundles of nerve fibers that act as high-speed communication cables in the brain. It shouldn’t be too shocking, then, to learn that fat is the single most important nutrient for protecting and preserving brain function. Eating a low-fat or, worse, a no-fat diet is actually the worst thing you can do for your brain. What the brain craves most are the omega-3 fats. They turn on the genes that determine how the brain develops, repair and preserve brain cells, enable the cells to deliver signals efficiently, and may even facilitate the growth of new cells. Studies show that without enough omega-3s, the brain can’t function properly. Over time, lack of omega-3s may even contribute to the development of Alzheimer’s disease. Unfortunately, most people don’t eat nearly enough of these good fats.