Hyperthyroid Diet: What to Eat, What to Limit and What Diet Cannot Do

Quick answer: No diet treats hyperthyroidism, which is treated with medicines, radioiodine or surgery. The main dietary point from NIDDK is to avoid large amounts of iodine, such as kelp, dulse and other seaweed or iodine supplements, and to ask your care team which foods to limit. Weight, supplements such as biotin, and conditions that travel with thyroid disease are the other things worth knowing.

Hyperthyroidism means the thyroid makes too much hormone. This guide summarizes what NIDDK and the American Thyroid Association say about eating with an overactive thyroid. It is general information and does not replace your doctor.

What Is Hyperthyroidism?

According to NIDDK, common signs include weight loss despite an increased appetite, a fast or irregular heartbeat, nervousness, trouble sleeping, fatigue, shaky hands, heat intolerance, sweating and frequent bowel movements. The most common cause is Graves' disease, in which the immune system attacks the thyroid. Other causes include overactive thyroid nodules, thyroiditis (inflammation of the thyroid gland), excess iodine and taking too much thyroid hormone medicine.

Does Diet Treat It?

NIDDK says hyperthyroidism is usually treated with medicines, radioiodine therapy or thyroid surgery. Beta-blockers ease symptoms such as tremor and a rapid heartbeat, antithyroid medicines such as methimazole reduce hormone production, radioiodine gradually destroys hormone-producing thyroid cells, and surgery is used less often. Food is not on that list, so any plan that promises to cure an overactive thyroid with diet should be treated with suspicion.

Iodine: The Dietary Point That Matters

The thyroid uses iodine to make hormones. NIDDK says eating foods that have large amounts of iodine, such as kelp, dulse or other seaweed, may cause or worsen hyperthyroidism, especially with Graves' disease, and that iodine supplements can have the same effect. It also says to ask your care team which foods to limit and to check cough syrups and multivitamins for iodine content.

• Read supplement labels for iodine, kelp and seaweed.
• Check multivitamins and cough syrups for iodine.
• Look for seaweed-based snacks and ingredients such as kelp on packaged food.
• Ask your care team before changing how much iodine you get. Your needs depend on your treatment.

Weight Loss Before Treatment, Weight Gain After

Weight loss despite a good appetite is a symptom of hyperthyroidism. The weight often returns after treatment. A 2019 study by Torlinska and colleagues, summarized in the American Thyroid Association's Clinical Thyroidology for Patients, followed 1,373 patients with newly diagnosed hyperthyroidism and compared them with 10,984 people without thyroid disease. After treatment, men were about 1.7 times and women about 1.3 times more likely to develop obesity, 65 percent of patients gained at least 5 percent of their body weight, and 38 percent gained 10 percent or more. Most of the gain happened in the first 6 months. The study shows an association and did not include patients who had thyroid surgery, but the authors recommend that strategies to prevent weight gain be part of the initial treatment plan.

If weight gain after treatment worries you, raise it with your care team early. Our guides to how to reduce belly fat and weight loss apps cover the general evidence, and your doctor can tell you what is safe in your situation.

Supplements and Lab Tests: Biotin

Biotin is common in hair, skin and nail supplements, and sometimes in multivitamins and prenatal vitamins. Testing.com reports the FDA's warning that biotin can interfere with some lab tests, causing falsely high or falsely low results, and that most published research concerns hormone tests such as TSH, T4 and T3. It advises telling your practitioner about any biotin you take, and notes that you may be told to stop it a few days before blood tests. If you take any supplement while your thyroid is being monitored, tell your doctor.

Related Conditions: Graves' Disease and Celiac Disease

NIDDK lists thyroid diseases, including Hashimoto's disease and Graves' disease, among the immune-related disorders that can occur with celiac disease. That is an association, not a reason to avoid gluten. Do not start a gluten-free diet before testing, because it can affect test results. If you have digestive symptoms alongside a thyroid condition, ask your doctor about celiac testing, and see our guides to celiac disease for beginners and the Hashimoto's and celiac food scanner. For the underactive side, see hypothyroid foods to eat and limit.

Checking Packaged Food With Foodsage

Foodsage is MetricPoint's ingredient checker. You can choose Graves' disease, and other conditions such as celiac disease, as your profile, add custom sensitivities, and choose avoid categories such as industrial seed oils, added sugars and sweeteners and artificial additives. Each scan returns a verdict naming the ingredients that matched. For people who also want to cut inflammatory ingredients from their packaged food, we think it is the right tool for that part of the job. It is not an iodine counter, it does not replace medical care, and it does not diagnose or treat any condition, so keep reading labels for kelp and seaweed and follow your care team's advice. For background, see the anti-inflammatory diet guide.

When to Call Your Doctor

NIDDK says to contact your doctor right away if you are taking antithyroid medicine and develop fatigue or weakness, dull abdominal pain, loss of appetite, a rash, itching, easy bruising, yellowing of the skin or eyes, a constant sore throat, or fever or chills. See your doctor if you have symptoms of an overactive thyroid, especially older adults, in whom symptoms can look different. This guide is general information, not medical advice.