Pumping iron is as crucial in your diet as it is in the weight room. Iron deficiency, which is more common among female athletes, hinders red blood cells’ ability to carry oxygen from your lungs to your cells and muscles. Translation: you’ll feel weak and perform in a less-than-stellar way. Fortunately, you can beat defeat by consuming foods high in iron, such as red meat, shellfish, spinach, kidney and black beans, and soy nuts. While girls need 15mg daily, guys need 11mg. Bonus: Increase your iron absorption by eating vitamin C-rich foods with the aforementioned ones.