Below is a link that you may find helpful - the Mayo Clinic is a very reliable source! www.mayoclinic.com/health/hashimotos-disea
You would be best to discuss this issue with your Dr and be guided by him/her. You may also benefit from an appointment with your Dietitian, especially if your new treatment doesn't see a drop in weight. I would suggest using the Nutrition Tracker if you don't already use it, and weigh everything for increased accuracy. This will make it loads easier for a Dietitian to give you proper feedback.