Anemia Diet happens when your body doesn’t have enough healthy red blood cells. The condition is mainly caused by blood loss, the destruction of red blood cells, or your body’s inability to create enough red blood cells. Red blood cells contain a protein called hemoglobin. Hemoglobin is full of iron. Without sufficient iron, your body can’t make the hemoglobin it needs to create enough red blood cells to deliver oxygen-rich blood throughout your body.