My Daughter Is 24 Years Old. She Was Very Active

My daughter is 24 years old. She was very active through high school, and has gained a considerable amount of weight since that time. However, her most bothersome issue now is leg cramps; mostly at night. She drinks a lot of liquids, and she does not seem to void as often as she should during the day, but she will get up several times at night. She has tried adding potassium and/or magnesium; if and when she gets some relief it doesn't last very long. What is best for these cramps; they have gone from the ankle down and/or from the thigh up through the lower back.