The thyroid is a small, butterfly-shaped gland in the neck. The gland produces hormones, including triiodothyronine (T3) and tetraiodothyronine (thyroxine or T4), responsible for controlling metabolism. They are vital for regulating body temperature, keeping organs running properly, amongst several other functions.

So when thyroid hormone levels are abnormal, metabolism is typically affected. The impact is dependent on the amount of thyroid hormone produced and can result in hypo- or hyperthyroidism.

What Is Hypothyroidism?

Hypo (meaning "low") thyroid can be very serious and life-threatening if left unmanaged. Also known as underactive thyroid disease, the thyroid gland does not produce sufficient thyroid hormones.

Eventually, metabolism slows down. Weight gain is the most well-known consequence of slower metabolism, though there are other symptoms to watch out for.

Symptoms of Hypothyroidism

A slowed-down metabolism can compromise a number of body functions. This can lead to many common hypothyroidism symptoms and signs including:

• Fatigue

• Increased sensitivity to cold environments

• Constipation

• Dry skin

• Thinning hair

• Facial puffiness

• Hoarseness

• Muscle weakness

• High cholesterol levels

• Muscle aches, tenderness, and stiffness

• Pain, stiffness, or swelling in the joints

• Heavier than normal or irregular menstrual periods in women

• Slower heart rate

• Depression and changes in mood

• Impaired memory

• Enlarged thyroid gland, which is medically known as a goiter

Knowing these signs of hypothyroidism is important, as prompt early detection and initiate proper treatment. What's more, up to 60 percent of those with thyroid disease are unaware of their condition.

Causes of Hypothyroidism

There are different types of hypothyroidism, and each one arises under varying circumstances in the body.

Hashimoto's disease, also known as chronic lymphocytic and Hashimoto's thyroiditis, is the most common cause of hypothyroidism. It is an autoimmune disease in which the patient's own immune system attacks and damages its own thyroid gland. The unresolved and constant damage of the thyroid gland causes hypothyroidism.

Not all cases are caused by Hashimoto's disease, though. Other causes of hypothyroidism may include:

• Thyroid cancer treatments, including radiation, and surgeries

• A genetic disease, including a birth defect that keeps the thyroid gland from developing properly

• Pregnancy can lead to the development of hypothyroidism for the same reason as Hashimoto's thyroid disease

• Disorders of the pituitary gland, such as a tumor

• Certain medications

• Nutrient deficiencies and toxicities, including those linked to iodine and vitamin D

The two main risk factors of hypothyroidism are age and sex. Other risk factors include a family history of thyroid disease or any autoimmune disease. Having type 1 diabetes, rheumatoid arthritis, or other autoimmune disorders increases the risk as well.

Treating Hypothyroidism

A clinical diagnosis of hypothyroidism poses the need for thyroid hormone replacement therapy. The standard treatment involves daily use of the synthetic thyroid hormone levothyroxine (Levo-T, Synthroid, others). This medication helps to restore thyroid hormone levels and reverse the signs and symptoms of hypothyroidism.

Complying to medication is imperative to restore thyroid function. Routine doctor visits help indicate current thyroid status and if any adjustments in medication are needed. This is important to lower the risks of complications of hypothyroidism.

Medication compliance and routine doctor visits are the core of hypothyroidism treatment. One can also benefit from making healthier lifestyle choices, including eating more nutritious foods for thyroid health and exercising regularly.

What Is Hyperthyroidism?

Conversely to hypothyroidism, hyperthyroidism causes excess thyroid hormones. Overproduction of these hormones subsequently elevates metabolism and increases the risk of weight loss.

Signs of Hyperthyroidism

One of the most significant symptoms of hyperthyroidism is weight loss. This is even with an increased appetite and food intake related to an elevated metabolism.

Other signs and symptoms of hyperthyroidism include:

• Increased sweating

• Heat intolerance

• Muscle weakness

• Agitation and nervousness

• Shortness of breath

• Irregular heart rhythms or heart palpitations

• Shakiness

• Vision changes

• Insomnia

Causes of Hyperthyroidism

Graves' disease is the most common cause of hyperthyroidism in the United States. It is an autoimmune disease that leads to over-activity of the thyroid gland. Other causes include, but are not limited to, the following:

• Too much thyroid medication

• Inflammation of the thyroid gland, clinically known as thyroiditis

• Excessive iodine intake

Treatment of Hyperthyroidism

Like hypothyroidism, treating hyperthyroidism involves medication, specifically antithyroid drugs. The most commonly used antithyroid drugs include methimazole and propylthiouracil.

Thyroid patients with an elevated gland may likewise benefit from radioactive iodine. This is given on a one-time basis and is mostly successful for restoring thyroid levels. However, hypothyroidism is a major complication of the treatment.

Surgery may be warranted, especially for those who do not respond well to medications and other treatments. Large thyroid glands that cause other health concerns, including difficulty swallowing and breathing, may require surgery.

Overall, always consult with a doctor for medical advice, diagnosis, and treatment options.

Thyroid Disease and Metabolism

The thyroid gland and hormones are responsible for controlling metabolism.

Simply put, metabolism is the total physiological process in which the body transforms calories from food into usable energy. This energy is used to carry out vital processes such as producing and repairing body cells and circulating oxygenated blood.

Ultimately, metabolism is ongoing and continues even when the body is at rest. Or, more formally known as a basal metabolic rate (BMR).

What Is Basal Metabolic Rate?

Basal metabolic rate is the rate of energy expenditure of a person at rest. It eliminates the variable effect of physical activity and accounts for 60 percent of total daily expenditure.

BMR can be determined with a simple equation: 24 X body weight in kilograms (kg)

To calculate the total daily energy expenditure, multiply the BMR by an activity factor. (I.e. 1.3 for sedentary, 1.5 for moderately active, and 1.7 for extremely active)

Take, for example, a 200 pound (200/2.2 = 91 kg) person who is moderately active.

BMR = 24 X 91 kg = 2184 calories per day X 1.5 activity factor

Total energy expenditure = 3,276 calories per day

While calories from foods are important to consider, there are nutrients of interest for those with hypo- and hyperthyroidism.

Hypothyroidism Diet Plan

While there is no hypothyroid diet per se, adopting a healthy eating pattern supplies adequate nutrition and moderates calories. There are additional nutrients that deserve attention for managing hypothyroidism.

Nutrients & Foods to Eat with Hypothyroidism

A diet rich in fiber, lean protein, and healthy fat naturally keeps calories in check while optimizing nutrient intake. The balance of nutrients is helpful for losing weight with hypothyroidism, as they likewise control hunger and keep blood sugars stable.

There are specific nutrients and foods of interest that may be helpful for easing hypothyroid symptoms.

• Iodine-rich foods: Iodine deficiency raises the risk of hypothyroidism. Iodine houses in the thyroid gland and assists in the production of thyroid hormones. The pairing of iodine and iron has also been shown to restore iodine deficiency and improve thyroid function. However, a low iodine diet may be warranted to increase the effectiveness of an upcoming iodine therapy.

Food sources of iodine include iodized salt, dairy products, eggs, saltwater fish, and soy. Multivitamins and supplements may contain a significant amount of iodine, too.

• Selenium: Selenium and thyroid disease is an area of interest, as supplementing with the mineral can improve hypothyroidism. Selenium is required for the antioxidant function and for the metabolism of thyroid hormones. Maintaining adequate selenium helps prevent thyroid disease and preserves overall health.

Brazil nuts, turkey, pork, beef, sunflower seeds, and shiitake mushrooms are rich sources of selenium.

Nutrients & Foods to Avoid with Hypothyroidism

Comprehensively, thyroid foods to avoid include highly processed and refined products that can trigger inflammation. People with hypothyroidism should also consider lowering or reducing the following:

• Goitrogens in cruciferous vegetables: Though plants tend to never be discouraged, produce containing goitrogens may be the exception to the rule. Goitrogens can inhibit thyroid activity, mostly by interfering with iodine uptake from the thyroid gland.

The compounds are mostly found in cruciferous vegetables, including cauliflower, broccoli, cabbage, Brussel sprouts, and turnips.

• Soy and soy products: Soybean has been explored to display goitrogen properties when iodine intake is scarce. However, a meta-analysis suggests soy supplementation has no effect on the thyroid hormones.

Reductions in soy products, including soy milk, tofu, tempeh, and miso, may be warranted if managing a thyroid condition.

• Gluten-containing products: A link exists between celiac disease and thyroid disorders, which may warrant a gluten-free diet (GFD). Some patients with celiac disease have reported a lower need for thyroid hormone replacement after complying to GFD. A gluten-free diet may bring clinical benefits to women with hypothyroidism related to an autoimmune disease, too.

Gluten is sourced from wheat, barley, and rye and the products the grains produce, including pastas and breads. Gluten may also be hidden in sauces, marinades, gravies, and other non-obvious sources.

Hyperthyroidism Diet Plan

Like hypothyroidism, there are certain nutrients foods for hyperthyroidism that can be helpful or harmful.

Nutrients & Foods to Eat with Hyperthyroidism

People with hyperthyroidism might experience weight gain. This is mostly due to an increased appetite paired with a high-calorie diet with limited physical activity.

Eating a nutrient-dense, balanced diet is key for combatting potential weight gain. Other specific nutrients and foods can be useful for lowering hyperthyroidism symptoms, too. These include:

• Low-iodine foods: A low-iodine diet may be prescribed if planning on radioactive iodine treatment. Products low in iodine include non-iodized salt, egg whites, plain-cooked grains, and unsalted nuts. Fresh meat, poultry, fresh-water fish, veggies, and fruits are considered low-iodine foods as well.

• Cruciferous vegetables: Whereas people with hypothyroidism should lower their intake, those with hyperthyroidism may benefit from cruciferous veggies. This is because they can help interfere with iodine use.

Eating selenium, iron, and other nutrient-dense foods may be of benefit for thyroid and overall health as well.

Foods to Avoid with Hyperthyroidism

There are many similarities between recommended hypo- and hyperthyroid dietary patterns. Common foods to avoid with hyperthyroidism include:

• Iodine rich foods, especially prior to radioactive iodine treatment.

• Soy, which may interfere with radioactive iodine treatment.

• Gluten, as celiac disease is more common in those with Graves' disease and other autoimmune disorders.

• Caffeine, which can worsen heart palpitations, insomnia, and other hyperthyroidism symptoms

Sample Meal Plan for Thyroid Disease

Overall, sticking to a healthy diet naturally reduces caloric intake when metabolism is slowed down. Because even with hyperthyroidism, eating nutrient-rich foods can lower inflammation in the body that often occurs.

A thyroid diet for weight loss and overall health should include whole foods s

• Whole grains, choosing whole grains over refined grains at least 50 percent of the time.

• Fruits and veggies, particularly choosing fresh varieties rather than those purchased with added sugar, salt, and other preservatives.

• Lean proteins and plant-based proteins, which may include poultry, eggs, and legumes.

• Milk and dairy products, in which low-fat varieties can further control calorie and saturated fat intake.

• Healthy fat sources, particularly those rich in unsaturated fatty acids such as olive oil and fatty fish.

A sample menu rich in nutrients and low in iodine, gluten, and other thyroid-related nutrients may look like the following:

Breakfast: Veggie omelet with cinnamon apple oats

Veggie omelet:

• 1/2 cup baby spinach
• 3 egg whites
• 1/4 cup mushrooms, chopped
• 1/2 bell pepper, chopped

Cinnamon apple oatmeal:

• 1/2 cup oats (made with water)
• ½ apple, chopped
• Cinnamon to taste

Snack: 1/4 cup unsalted nuts

Lunch: Chopped chicken salad with 1 orange

Chopped chicken salad:

• 2 cups of chopped salad greens
• 3 ounces of chopped chicken
• 1/2 cup of chopped cucumbers
• 1 Tbsp chopped pecans
• 1 to 2 Tbsp olive oil or low-salt dressing

Snack: 1 cup carrot sticks with 2 Tbsp hummus

Dinner: Roasted turkey, rice, and broccoli

Roasted turkey breast with cranberry chutney:

• 5-ounces turkey breast
• 1/4 cup cranberry chutney
• 1/2 cup butternut squash and wild rice blend
• 3/4 cup broccoli

All in all, a primary care provider, dietitian, or another healthcare professional should help determine a thyroid diet. This is because nutrients needs vary from one person to the next based on thyroid function and other factors. Certain nutrients and foods can impact medication use as well.