Patti UT:
I can understand why you're bummed out over your weight gain, post-AN surgery, especially as a physically active person.
Ironically, I had just the opposite experience. Prior to my diagnosis and subsequent surgery, I had been losing weight; just over 30 pounds within 6 months,...and believe me, I wasn't trying, although I was about 25 pounds over my 'ideal' weight range before my appetite diminished and the pounds began to simply drop off. In fact, one of the motivations for my initial doctor visit was my 'mysterious' weight loss and diminished appetite. My Primary Physician only wanted an MRI scan to check my sinuses, hoping to find a reason for my loss of taste (and related loss of appetite) but, instead, he found a large, almost-intimidating (4.5 cm) AN tumor. A hospital nurse told me that this happens a lot. Doctors have patients that present with symptoms that appear to be one thing but a CAT or MRI scan shows something entirely different, such as, in my case, an AN. A really big AN, at that.
Since the (successful) AN surgery, my appetite has returned and I'm eating as much as I ever did - and throughly enjoying it (don't hate me). Pre-op, I had some CAT-scans done that inncluded my stomach, and everything was 'perfectly normal'. A few weeks after my AN surgery, I consulted a gastroenterologist who looked at the CAT-scan report that involved my stomach and intestinal tract and he stated there was nothing he could see in the report that indicated any abnormalities. He also mentioned that some of the prior weight loss 'may' have been stress-related, which made sense. What made even more sense was when my neurosurgeon informed me that the AN tumor he removed had involved some of the nerves that effect the tongue and so, it must have had a negative impact on my sense of taste, likely causing the decrease in my appetite and subsequent loss of weight. I still have a slight touch of numbness on one side of my tongue - but my appetite has not been negatively effected - at all. I have gained a few pounds but am well within my normal weight range for my height and build. I've always had a 'high metabolism rate' which appears to have returned after deserting me for some years. I now weigh about what I weighed 25 years ago, when I was a lad of 38. I'm fairly active and I walk as much as possible but other than that, I do little 'formal' exercise and I eat pretty much what I please, as always.
I know that all this doesn't directly address your specific situation, and I trust some other posters will do that for you, but I wanted to point out that we are all individuals and, for better or worse, there is little pattern to our experiences with AN.