30 years ago I had a partial thyroidectomy for a benign tumour. Three weeks ago I had a very large dose of radio iodine to treat hyperthyroidism(multi nodular goitre). My weight has always been the same and my diet and lifestyle have not changed but I am putting on weight very rapidly what can I do to stop this and lose the weight I have gained. I am not yet on thyroxine and have not had a blood test yet so I do not know if I am hypothyroid. I was asymptomatic with hyperthyroidism and appear to be the same since the radio iodine treatment apart from the weght gain