If you are on diuretics (fluid pills) this can cause low potassium levels. Too much vomiting if you are sick or have been sick can cause low potassium levels. Low potassium is a symptom of another disease or condition. The normal concentration of potassium in the body is regulated by the kidneys through the excretion of urine. The body needs potassium for the contraction of muscles (including the heart), and for the functioning of many complicated proteins (enzymes). Potassium is found primarily in the skeletal muscle and bone, and participates with sodium to contribute to the normal flow of body fluids between the cells in the body. Eating foods with Potassium does help such as banannas. But if you are on diuretics as I am sometimes you may have to take Potassium pills to keep it more balanced. Click this link if you would like more info: http://www.webmd.com/a-to-z-guides/Hypokalemia