Weight Loss on Aldactone

I have PCOS and have finally found a combination of medication that seems to be helping with my weight in addition to watching my carbs and walking more. My RE just put me on Aldactone (100mg) about 3 months ago to reduce my androgens and I have been on metformin es for over a year. I have been losing weight slowly but surely :-) since I made dietary changes, about 30 pounds. But since I started the Aldactone as well, I am now down 54 pounds. Is this common? Can I expect this to continue?