I have Hashimotos disease and have been on Thyroxine for five years. Recently I ve been suffering significant weight gain although I haven t changed my well balanced diet , and have increased my exercise regime (walking, yoga and pilates). I ve also been waking at night with a thumping heart and a feeling of extreme anxiety . This sometimes happens during the day as well. Additionally I m experiencing a reduction in mental ability. I went to a local GP who did an ECG which was fine, and blood tests which indicated that my thyroid was overactive and I need to reduce my thyroxine dosage from 100mcg per day to 75mcg per day, which I ve done. My concern is that since that diagnosis a week ago I ve put on another kilo, and am now the heaviest I ve ever been, except during both my pregnancies, and feel extremely uncomfortable. I am concerned that the diagnosis should have been one of an under-active thyroid, although I am not experiencing other symptoms such as constipation, hair loss etc. I m not sure what to do from here but I do know this fast weight gain is not normal. What do you suggest ?