1. Get adequate calories
2. Don't go VLC. Less than 50 grams of carbs a day may inhibit thyroid hormone T4 conversion to T3
3. Get adequate selenium-200mcg/day
4. Get optimal vitamin D
5. Be aware of anemia, low ferritin
6. Be careful with exercise as it can stress the body. If you do have thyroid issues over exercising is not a good idea.
7. Look into foods that can impact thyroid function. All About Goitrogens - Why Thyroid Patients Are Warned About Cruciferous Vegetables