hello user , i understand your concerns . propanolol and other beta blockers are very common and effective drugs used to treat tremors and can cause weight gain in some persons , however usually not more than 2-3 kgs - in your case hypothyroidism seems the main factor responsible , slowing down the metabolism in body - so appropriate treatment for that needs to be continued by your endocrinologist - There are other medicines to treat tremor like benzodiazepines , primidone etc but they have got their own range of side effects - if your tremor is controlled with propanolol , you should need not much worry anout the weight gain until it keeps on increasing despite adeuate thyroid levels and exercise after few months . Take care