I have gained over 10lbs since my total thyroidectomy 4 months ago and i eat a lot. is this normal to gain the weight?

Not usually: First of all, it is important to return to your endocrinologist or internist to have your thyroid levels checked. It is possible that you are not taking enough thyroid medication. It would also depend on the reason for having the total thyroidectomy. If is was for an overactive thyroid, your metabolism might have been "revved up" before surgery and now, if normal, you could gain weight easily.