What Causes Weight Gain After A Hysterectomy?

Good afternoon, I had a (LAVH) Da Vinci Robotic Surgery on Monday, April 28, 2014 which included a Hysterectomy with Bilateral Salpingo Oophorectomy due to the presence of a fibroid tumor on my cervix in addition to a tubular cyst that was discovered during the surgery. I am 55 years old, 4 years post-menopause and have been on HRT (Estradiol patch and Prometrium) for approximately the last ten years. I am in excellent health overall with a pre-surgical height and weight of 5 8 , 139 pounds. I immediately gained 15 pounds post-surgery and am now down 10 pounds due to drinking lots of water and having my digestive system now in better working order! I still feel very bloated and am wondering if this excess weight is due to continued edema that may be present in abdominal tissues or is it due to my biological/hormonal response to the Hysterectomy? I expected my weight to be (somewhat) less after the surgery and am surprised (not to mention disappointed) that I am already faced with weight gain! Perhaps I made a mistake by even stepping on the scale in the first place at this point in time! Can you provide some reassurance that this is normal and to be expected or is this possibly due to the lack of my normal exercise routine that I have been accustomed to doing for the last five years? Thanks very much for your recommendations and professional advice.