Taking Meds that cause weight gain?

Lov3lif3

I take Northisterone to stop my periods (they were heavy and painful and I've been sterilised so don't need the Pill), and I hvae noticed in the last 2 years of taking them a gain of 1.5stone. Now I know that weight gain is a side effect and I'm not blaming the medication alone. I am not sure whether to stop taking them and to risk the obvious coming back, or to carry on. There is only 1 alternative medication and it has the same side effects, so that is out!

Question is.. I start the counting cals diet tomorrow morning, is there anything else I can do, so that I can carry on taking the medication and still loose weight?

Thank you x