I have to add my experience to this - I did not have radiation or chemo, however, 2 1/2 months before my partial glossectomy/ND I had a laparoscopic bowel resection for an unrelated problem - so combined lost about 15 pounds, although I gained a little back from 1st surgery before the second. I am still 10 pounds under what I normally weighed for the last 10 years, and also don't seem to gain although I too am not as careful as I used to be about what I eat - I am still a healthy eater but I do also tend to eat more of those things I always stayed away from before, like desserts, bread, etc. I have always been active and am a bike rider - pretty much back to my pre-surgery exercise regime... I weigh myself often thinking soon the eating more will catch up with me - I have always gained weight very easily in the past and had to be very careful - but it hasn't caught up with me yet, either. No idea why...