What Causes Weight Gain Post Parathyroidectomy?

I had one of my parathyroid glands which had an adenoma on it removed last July. Within weeks I gained 5 pounds and have since put on another 5 pounds which is really upsetting me since I don t eat sweets or desserts due to hypoglycemia. My specialist says it s nothing to worry about. I wish to know if the surgery could have caused my weight gain and how I can lose it? Thank you.