The foods you crave during your period, such as chocolate, can cause mood swings and fatigue, according to Dr. Pankaj Singhal of New York Gynecology Surgery and Endometriosis. These cravings are often misunderstood as signs of real biochemical shifts, which can make a difficult week significantly worse. Chocolate, a magnesium-rich food, is particularly bad for its sugar-spiking and crashing insulin, which worsens mood swings. Experts suggest swapping milk chocolate for 70% or higher dark chocolate, which will provide magnesium without the inflammatory load. Other foods such as pumpkin seeds, almonds, and sauteed leafy greens may also satisfy your need for magnesium.