Hello
Thanks for putting your query over here.
The cramps you experience is because of 
hypokalemia caused due to diuretics.
Firstly ,I want to know do you have any medical conditions for which you have been prescribed diuretics by cardiologist?If you have visited cardiologist you must be definitely having some other symptoms.
Diuretics help only temorarily in 
weight loss by causing water loss from body.It can be harmful at times.
Permanent and healthy weight loss is through healthy diet and regular exercising only except in 
morbid obesity or when other medical conditions are present.
If the use of diuretics is mandatory,potassium sparing diuretic like 
spironolactone can be used as an alternative.
You may talk with your treating physician regarding all this.
Hope I answered your query.
Feel free to ask any more doubts.