Step one: Gluten is associated with autoimmune disorders because of a protein called zonulin. Molecules that shouldn’t to enter the bloodstream get through because of zonulin. This triggers an immune response that can never fully resolve. Remove gluten.  I offer the most comprehensive lab test on gluten. It only just became available in Canada this year.   
Step two: Cortisol is anti-inflammatory and therefore important in any immune response. If stress management is not central to treatment this hormone will have a negative impact on the thyroid especially if it is under an autoimmune attack. Cortisol spikes at night and may cause night hunger. A high protein snack before bed can help.
Step three: Having sufficient iodine in the diet is critical. Often 800 mcg of iodine is suggested for a period of time. Brazil nuts are high in selenium as is fish. Kelp and bladderwrack are good sources for iodine. Eating a variety of sea vegetables is good.
Step four: Add 300-500 mg magnesium glycinate at night is helpful for a variety of reasons including metabolic.
Step five: Dietary advice includes reducing nitriles and goitrogenic foods. Cooking these reduces the negative effects.
Step six: A moderate carbohydrate diet (around 30% of total calorie intake) is recommended as thyroid hormone conversion requires adequate amounts.
Step seven: Studies shows diabetics often have thyroid disorders. This is a bidirectional relationship, meaning thyroid disorders increase blood sugar problems and vice versa. Chronically high blood sugar leads to insulin resistance and inflammation. Repeated insulin surges increase the destruction of thyroid gland.
Step eight: Improving gut health is critical for all forms of thyroid disease. An autoimmune protocol is a starting place with individual variation that is found by experimenting. Thyroid hormones affect the tight junctions of small intestine and stomach. lipopolysaccharides, an endotoxin from the cell walls of pathogenic bacteria, can escape the gut and trigger an autoimmune reaction. This leads to inflammation and a decrease in thyroid hormone production. I recommend sweet potatoes, yams, plantains, taro, yuca, and winter squashes for adequate starches with fermented veggies as a condiment. A wide variety of other proteins, fats and plants can be eaten. Removing nightshades, eggs, nuts and seed is a standard autoimmune protocol as many react to these foods.
Step nine: Selenium deficiency is common and more so with those with gut issues and inflammation. Adequate selenium protects against the effects of iodine toxicity. Selenium is needed for the conversion of T4 to T3. Supplementation has been shown to reduce TPO antibodies and inflammatory activity Hashimoto’s.
Step ten: The cycle of low blood sugar leading to increased cortisol from the adrenal glands in order to promote glucose production. Cortisol is a glucocorticoids meaning that its role is to increase the amount of glucose available to the brain and muscles. Its will curb digestion, growth, and reproduction in order to do this. Continual release of cortisol can suppress the pituitary and therefore thyroid hormone output. Repeated cortisol release caused by episodes of low blood sugar can suppress pituitary function and reduce thyroid hormone output. Hypothyroidism will affect metabolic rate by reducing glucose sensitivity. Hypoglycemia can result and trigger more cortisol and this is a vicious cycle. Stress reduction is a very important part of treatment. Stress often induces and can exacerbate autoimmune disease, insulin-resistant hormone imbalance, and reduce total thyroid hormone output. It increases inflammation, decreases T4 to T3 conversion and weakens the immune barriers in the gut and brain. Stress reduces sensitivity to thyroid receptors leading to thyroid resistance. It also impairs estrogen clearance and increases thyroid-binding globulin levels. You can see why blood sugar and cortisol need to be understood in relation to one another especially when looking at thyroid hormone.