If i have an overactive thyroid and take medication for it, will it help me lose weight?

Likely not: Treatment of an overactive thyroid aims to make your thyroid hormone levels normal. Thsi will also normalize your metabolism (it will slow down, as compared to when you were hyperthyroid). It is very important to decrease caloric intake as most likely as metabolism slows down, if eating the same amount of calories, you will gain weight.