Hello, First of all, I want to be certain you are taking your medication correctly as it makes a huge difference in thyroid function. Take on an empty stomach at least 20 minutes before eating anything and 4 hours before any vitamins/minerals/supplements. Many people take their medication wrongly. To suggest any specific diet for you ask your doctor if she has tested you for Hashimotos, done a urinary iodine test or checked selenium level. The differing forms of thyroid disease have specific nutritional approaches. I need more information on the type of thyroid disorder you have. Thyrox is the synthetic T4 hormone. T4 needs to be converted to T3, the active form and selenium is involved in this step. Many people do not get the selenium they need to make a good conversion rate. While taking Thyrox for weight loss purposes will not work, but taking it to normalize thyroid function will help maintain caloric balance when combined with proper nutrition and exercise. To lose weight, optimize thyroid function through appropriate diet. I need to know what type of thyroid disorder you have to give you the general guidelines for your specific type.Also, you should be on the correct dosage of medication and co-factors. Did you get a total thyroid work up aside from the above? Measure auto-antibodies? Scan your thyroid? Your levels are out of range and that is a huge jump in Thyrox (mcg, not mg) without a complete panel being run. To lose weight, exercise more intensely and frequently. Eat half the portions you eat now but not lower than 1200 calories/day. Cut out all foods with added sugars, decrease saturated fat, iodized salt, salt in general (sodium 2300 mg); eat fresh fruits and vegies, don t drink your calories. Increase fiber to 25 g/day, this will decrease hunger. Increase slowly and add more water to your diet along with the increased fiber so the fiber can expand and function properly. After the suggested tests are run and your type of hypothyroid is clarified I further advise a visit to a Registered Dietitian Nutritionist for proper diet and meal planning tailored to you as an individual and to be there for ongoing support when needed. Oh, and your last question about how long must you take your thyroid medication. For life. Regards, Kathryn Shattler, MS,RDN