hi sandie_swan, I also had a thyroidectomy 4 yrs ago and was always very thin beforehand - found it easy to lose weight. Since my surgery I have put on 10kgs and find it impossible to lose (like you, I've tried eating healthy, even eating very little) and nothing seems to work. I am now eating healthy and exercisng regularly but still, the most I will lose is a couple of kilos. I dont' know the answer sorry, I've just assumed I will have to live with it!