Diabetes insipidus- can't lose weight

My wife had a pituitary adenoma removed 2 years ago and has had diabetes insipidus ever since. She takes desmopressin nasal spray and has been unable to lose weight on it.  Even with weights, cardio, walking miles a day- nothing but water retention.  She might ask her doctor to lower the dose but we can't find any solutions online. Any suggestions would be great!

What dose does she have currently?

She is currently taking a 0.1 mL (10 mcg) spray twice a day.  She called her dr and asked if it could be lowered a bit but hasn't received a response yet. 

I have had Diabetes Insipidus since 1990 and all my endocrinologists have told me to take desmopressin as needed. That doesn't work for the pharmacies/insurance providers though because they need an exact amount. So what my doctors have to do is write a prescription for a reasonable amount but they instruct me to take it as needed.

Does your wife feel that she is experience water retention and that is what is causing the weight problem?  

Before she had surgery to remove the adenoma she was able to quickly lose weight. After, however, as soon as she started weight lifting, she gained weight steadily for several months. Frustrated, she quit exercise altogether and lost maybe 15 or 20lbs rapidly. She attempted to lift again recently but gained the weight again. We aren’t sure if it’s all water weight. The only factor that has changed since the surgery is the desmopressin.  Hopefully the endo will give her a .5 dose or similar to try.