Food that is high in animal fat confuses the brain and can cause you to eat too much, according to a study published in the September issue of the Journal of Clinical Investigation. Researchers at the University of Texas Southwestern Medical Center concluded that the palmitic acid found in foods with saturated fat—such as beef and dairy products—quickly makes the brain resistant to signals from leptin and insulin, two weight-regulating hormones that tell the brain when the body is full. Without these signals it is easier to overeat, and this hormone resistance can last for up to three days. The research suggests that only fat containing palmitic acid has this effect, so plant-based fats such as olive oil are in the clear.