I am trying to prevent the weight gain also. I am 1 year out from the end of my chemoradiation. I wanted to stay at my post treatment weight and perhaps even lose some more (138, 5'2" &73). I am now 148. Why?
Because I eat too many starchy/bad carbs. I don't eat enough protein - need 90 g per day....and because my metabolism complex drives a need to nap.
Everyone is different. Everyone's cancer story is different and our recovery is ours to shape.
I am continuing to learn about the missing thyroid, Levothyroxine, and the brain, pituitary gland etc. It's very complex. I understand the answers I get from Gemini. My endocrinologist doesn't explain much.
I know what I have to do. I just have to do it (eat ultra healthy and balanced). I will walk more to offset the naps.
Best wishes for good health.